* Add recovery code support for two-factor auth

When users enable two-factor auth, the app now generates ten
single-use recovery codes. Users are encouraged to print the codes
and store them in a safe place.

The two-factor prompt during login now accepts both OTP codes and
recovery codes.

The two-factor settings UI allows users to regenerated lost
recovery codes. Users who have set up two-factor auth prior to
this feature being added can use it to generate recovery codes
for the first time.

Fixes #563 and fixes #987

* Set OTP_SECRET in test enviroment

* add missing .html to view file names

* Simplify admin/reports controller filtering for index

* Rename parameter to resolved

* Fix issue where reports view could not access filter_link_to

* Add coverage for admin/reports controller

* DRY up resolution of related reports for target account

* Clean up admin/reports routes

* Add Report#statuses method

* DRY up current account action taken params

* Rubocop styles

* Add request spec for host meta route returning xml

* Add routing spec for xrd routes

* Update well-known routes

* Move webfinger and host-meta actions to their own controllers

* Remove unused account_params method in admin/accounts controller

* Introduce AccountFilter to find accounts

* Use AccountFilter in admin/accounts controller

* Use more restful routes admin silence and suspension area

* Add admin/silences and admin/suspensions controllers

* Refactor Export to take an account and know about the export types

* Use Export instance in settings/exports#show

* Allow export of mutes list

* Allow importing of mutes list

* Refactor to use Settings::Exports::BaseController and DRY up exports code

* Add coverage for embedded status view

* Refactor embed view to eliminate @external_links variable

The spec was checking the activity_id of the activities held in notifications
within the controller.

Because the activities are different models, it is possible that they are
created with the same database IDs, and when they are this spec fails because an
activity which should not count as a match is counted as one.

* Add basic coverage for settings/exports controller

* Remove unused @account variable from settings/exports controller

* Add coverage for download export actions

* Remove deprecated `render :text` in favor of `send_data` for csv downloads

* Add model to handle exports

* Use Export class in settings/exports controller

* Simplify settings/exports controller methods

* Move settings/export to more restful routes

* Add spec for settings/imports controller

* Add failing spec for settings/imports#create

* Fix broken imports

* Refactor ImportWorker

* Add exclude_types param to /api/v1/notifications

* Exclude notification types in web UI through exclude_types in the API

* Consolidate webfinger string creation under Account#to_webfinger_s

* Introduce Account#local_username_and_domain for consolidation

* Add Admin::BaseController to wrap admin area

Extracts the setting of the `admin` layout and verifying that users are admins
to a common base class for the admin/ controllers.

* Add basic coverage for admin/reports and admin/settings controllers

* Allow users to update their Account in the API

It would be nice for API clients to be able to allow users to update
their accounts without having to wrap Mastodon in a web view. This patch
adds an API endpoint to let users submit a PATCH for their account.

Signed-off-by: David Celis <me@davidcel.is>

* Add /api/v1/accounts/update_credentials to the API docs

Signed-off-by: David Celis <me@davidcel.is>

* Add InstancePresenter to expose site details

* Clean up about controller, use instance presenter

if account lock info was up to date, otherwise re-do the FollowService
with now updated information

redis-backed "mentions" timeline as redundant (given notifications)

application website validation, don't link to app website if website isn't set,
also comment out animated boost icon from #464 until it's consistent with non-animated version

Filters out hidden stream entries from Atom feed
Blocks now generate hidden stream entries, can be used to federate blocks
Private statuses cannot be reblogged (generates generic 422 error for now)
POST /api/v1/statuses now takes visibility=(public|unlisted|private) param instead of unlisted boolean
Statuses JSON now contains visibility=(public|unlisted|private) field

removing web app capability from non-webapp pages

resources that require a user context vs those that don't (such as public timeline)

/api/v1/statuses/public   -> /api/v1/timelines/public
/api/v1/statuses/home     -> /api/v1/timelines/home
/api/v1/statuses/mentions -> /api/v1/timelines/mentions
/api/v1/statuses/tag/:tag -> /api/v1/timelines/tag/:tag