Fixes CVE-2018-8048 and CVE-2018-3740, two medium-severity XSS
vulnerabilities present in these gems when built against
libxml2 >= 2.9.2.

* update to new version of devise_pam_authenticatable2

* fix behaviour if suffix is nil, fix environment loading, fix user email creation

* code cleanup/fix linter warning

* Revert "Bump version to 2.3.2rc1"

This reverts commit cdf8b92fea.

* Revert "Downgrade Dockerfile to Ruby 2.4.3 on Alpine 3.6 (#6806)"

This reverts commit 0074cad44f.

* Revert "Handle Mastodon::HostValidationError when pulling remoteable assets (#6782)"

This reverts commit 4a0a19fe54.

* Revert "Correct the reference to user's password in mastodon:add_user task (#6800)"

This reverts commit 338bff8b93.

* Revert "Upgrade Paperclip to version 6.0.0 (#6754)"

This reverts commit b88fcd53f7.

Fixes CVE-2017-11428

* Fix #201: Account archive download

* Export actor and private key in the archive

* Optimize BackupService

- Add conversation to cached associations of status, because
  somehow it was forgotten and is source of N+1 queries
- Explicitly call GC between batches of records being fetched
  (Model class allocations are the worst offender)
- Stream media files into the tar in 1MB chunks
  (Do not allocate media file (up to 8MB) as string into memory)
- Use #bytesize instead of #size to calculate file size for JSON
  (Fix FileOverflow error)
- Segment media into subfolders by status ID because apparently
  GIF-to-MP4 media are all named "media.mp4" for some reason

* Keep uniquely generated filename in Paperclip::GifTranscoder

* Ensure dumped files do not overwrite each other by maintaing directory partitions

* Give tar archives a good name

* Add scheduler to remove week-old backups

* Fix code style issue

* Fix avatar and header issues by using custom geometry detector

Revert a part of #6508. The file passed to dynamic styles method
was not actually a file, but an instance of Paperclip::Attachment,
which broke all styles by always returning {} from the method.

One problem with GIF avatars was that Paperclip::GeometryDetector
reported wrong dimensions for them, e.g. 120x120 GIF avatar would
for some reason be detected as 120x53. By writing our own geometry
parser, we can use FastImage, which also happens to be faster than
ImageMagick, to detect image dimensions, which are also correct.

Unfortunately, this PR does not implement skipping a `convert`
entirely if the dimensions are already correct, as I found no easy
way to write that behaviour into Paperclip without rewriting the
Paperclip::Thumbnail class.

* Only invoke convert if dimension or format needs to be changed

* Save metadata from video attachments, put correct dimensions into OG tags

* Add twitter:player for videos

* Fix code style and test

* Add better CLI prompt

* Add rake mastodon:setup interactive wizard

* Test db/redis/smtp configurations and add admin user at the end

* Test database connection even when database does not exist yet

Unlike strip_tags, html2text will preserve text present in other nodes,
e.g. anchor tags:

    [1] pry(main)> str = '<a href="http://www.example.com">A link</a>'
    => "<a href=\"http://www.example.com\">A link</a>"
    [2] pry(main)> Html2Text.convert(str)
    => "[A link](http://www.example.com)"
    [3] pry(main)> include ActionView::Helpers::SanitizeHelper
    => Object
    [4] pry(main)> strip_tags(str)
    => "A link"

Preserving the href of an anchor allows keyword mutes to also match on
URLs, which is something that the frontend regex filter can currently
do.

* Add full-text search for authorized statuses

- Search API will return statuses that match the query
- Only for logged in users
- Only if you are author of the status,
- Or you were mentioned in it
- Or you favourited or reblogged it
- Configuration over `ES_ENABLED`, `ES_HOST`, `ES_PORT`, `ES_PREFIX`
- Run `rails chewy:deploy` to create & populate index

Fix #5880
Fix #4293
Fix #1152

* Add commented out docker-compose configuration for ES container

* Optimize index import, filter search results

* Add basic normalization to the index

* Add better stemming and normalization to the index

* Skip webfinger request if search query includes both @ and a space

* Fix code style

* Visually separate search result sections

* Fix code style issues

* Cas authentication feature

* Config

* Remove class_eval + Omniauth initializer

* Codeclimate review

* Codeclimate review 2

* Codeclimate review 3

* Remove uid/email reconciliation

* SAML authentication

* Clean up code

* Improve login form

* Fix code style issues

* Add locales

* add pam support, without extra column

* bugfixes for pam login

* document options

* fix code style

* fix codestyle

* fix tests

* don't call remember_me without password

* fix codestyle

* improve checks for pam usage (should fix tests)

* fix remember_me part 1

* add remember_token column because :rememberable requires either a password or this column.

* migrate db for remember_token

* move pam_authentication to the right place, fix logic bug in edit.html.haml

* fix tests

* fix pam authentication, improve username lookup, add comment

* valid? is sometimes not honored, return nil instead trying to authenticate with pam

* update devise_pam_authenticatable2 and adjust code. Fixes sideeffects observed in tests

* update devise_pam_authenticatable gem, fixes for codeconventions, fix finding user

* codeconvention fixes

* code convention fixes

* fix idention

* update dependency, explicit conflict check

* fix disabled password updates if in pam mode

* fix check password if password is present, fix templates

* block registration if account is maintained by pam

* Revert "block registration if account is maintained by pam"

This reverts commit 8e7a083d65.

* fix identation error introduced by rebase

* block usernames maintained by pam

* document pam settings better

* fix code style

Mitigation for CVE-2017-0889.

https://www.cvedetails.com/cve/CVE-2017-0889/
https://medium.com/in-the-weeds/all-about-paperclips-cve-2017-0889-server-side-request-forgery-ssrf-vulnerability-8cb2b1c96fe8

- premailer gem to turn CSS into inline styles automatically
- rework UserMailer templates
- reword UserMailer templates

* Add confirmation step for email changes

This adds a confirmation step for email changes of existing users.
Like the initial account confirmation, a confirmation link is sent
to the new address.

Additionally, a notification is sent to the existing address when
the change is initiated. This message includes instruction to reset
the password immediately or to contact the instance admin if the
change was not initiated by the account owner.

Fixes #3871

* Add review fixes

* Remove rabl dependency

* Replicate old Oj configuration

* Update active_model_serializers to version 0.10.7

* Update capistrano-rails to version 1.3.1

* Update capistrano-rbenv to version 2.1.3

* Update capybara to version 2.16.1

* Update devise-two-factor to version 3.0.2

* Update i18n-tasks to version 0.8.19

* Update ox to version 2.8.2

* Update parallel_tests to version 2.19.0

* Update puma to version 3.11.0

* Update redis-namespace to version 1.6.0

* Update rspec-rails to version 3.7.2

* Update scss_lint to version 0.56.0

* Update webmock to version 3.1.1

* Update webpush to version 0.3.3

* bundle update

jwt 2.1.0 still does not work well.
ref. https://github.com/zaru/webpush/issues/42

* Update better_errors to version 2.4.0

* Update binding_of_caller to version 0.7.3

* Update bootsnap to version 1.1.5

* Update browser to version 2.5.2

* Update capistrano to version 3.10.0

* Update capistrano-bundler to version 1.3.0

* Update capistrano-rbenv to version 2.1.2

* Update capybara to version 2.15.4

* Update cld3 to version 3.2.1

* Update fabrication to version 2.18.0

* Update fog-openstack to version 0.1.22

* Update kaminari to version 1.1.1

* Update lograge to version 0.7.1

* Update nokogiri to version 1.8.1

* Update oj to version 3.3.9

* Update ox to version 2.8.1

* Update parallel_tests to version 2.17.0

* Update pkg-config to version 1.2.8

* Update rspec-rails to version 3.7.1

* Update rubocop to version 0.51.0

* Update scss_lint to version 0.55.0

* Update sidekiq to version 5.0.5

* Update sidekiq-scheduler to version 2.1.10

* Update tzinfo-data to version 1.2017.3

* Update webpacker to version 3.0.2

* bundle update

* Close connection when succeeded posting

* Update webmock

* Bump ruby version to 2.4.2

https://www.ruby-lang.org/en/news/2017/09/14/ruby-2-4-2-released/

Gemfile.lock is also updated.

TODO
- [ ] Update Dockerfile with Alpine release of ruby-2.4.2

* Revert jwt version

It seems that jwt 2.0.0 fails in some environment.
ref. https://github.com/zaru/webpush/issues/42

* Bump Ruby version on docker image

Bumps [puma](https://github.com/puma/puma) from 3.9.1 to 3.10.0.
- [Release notes](https://github.com/puma/puma/releases/tag/v3.10.0)
- [Changelog](https://github.com/puma/puma/blob/master/History.md)
- [Commits](https://github.com/puma/puma/compare/v3.9.1...v3.10.0)

Bumps [rails](https://github.com/rails/rails) from 5.1.3 to 5.1.4.
- [Commits](https://github.com/rails/rails/compare/v5.1.3...v5.1.4)

* Fix language filter codes

CLD3 returns BCP-47 language identifier, filter settings expect
identifiers in the ISO 639-1 format. Convert between formats,
and exclude duplicate languages from filter choices (zh-CN->zh)

* Fix zh name

* Add handling of Linked Data Signatures in payloads

* Add a way to sign JSON, fix canonicalization of signature options

* Fix signatureValue encoding, send out signed JSON when distributing

* Add missing security context

* Update twitter-text to version 1.14.7

* Update tilt to version 2.0.8

* Update statsd-instrument to version 2.1.4

* Update sidekiq to version 5.0.4

* Update sidekiq-scheduler to version 2.1.8

* Update sidekiq-unique-jobs to version 5.0.9

* Update redis-activesupport to version 5.0.3

* Update rails-settings-cached to version v0.6.6

* Update pkg-config to version 1.2.4

* Update parallel_tests to version 2.14.2

* Update jsonapi-renderer to version 0.1.3

* Update i18n-tasks to version 0.9.16

* Update httplog to version 0.99.7

* Update fabrication to version 2.16.2

* Update bootsnap to version 1.1.2

* Update aws-sigv4 to version 1.0.1

* Update aws-sdk-core to version 2.10.21

* Update hashdiff to version 0.3.5

* Update rails to version 5.1.3