Closes https://github.com/tootsuite/mastodon/issues/3102

Since Rails 5.1 missing migration version results in following error:

```
StandardError: Directly inheriting from ActiveRecord::Migration is not supported. Please specify the Rails release the migration was written for:
```

This PR fixes all migration files.

* i18n Update : Add preference setting for delete toot modal

Adding a line for "Add preference setting for delete toot modal"

* i18n update for pin/unpin

Update to add two more translations

* i18n update to have the dates in plain occitan

* Removed the blank line

* %{selft} back in the translation

* Update annotate to version 2.7.2

* Update puma to version 3.9.0

* Update aws-sdk to version 2.9.28

* Update bootsnap to version 1.0.0

* Update nio4r to version 2.1.0

* Update nokogumbo to version 1.4.12

* Update oj to version 3.0.11

* Update pkg-config to version 1.2.3

* Update rubocop to version 0.49.1

* Update sidekiq-scheduler to version 2.1.5

* Added support for configurable reserved usernames

* Added reserved usernames from mastodon issue 1355

* Fix reserved usernames

* Update axios to version 0.16.2

* Update css-loader to version 0.28.4

* Update postcss-smart-import to version 0.7.4

* Update react-immutable-pure-component to version 0.0.5

* Update stringz to version 0.2.1

* Update style-loader to version 0.18.1

* Update websocket.js to version 0.1.9

* yarn upgrade

* Do not fall back to StreamEntry if object_type is unavailable in TagManager

Since 6d6a429af8fe4bd92ed497f401676353fdc603e0, when Status, the only model
with stream_entry, and StreamEntry got its own logic in uri_for and
url_for, the purpose of the fallbacks to activity_type of StreamEntry
became unclear.

This commit removes the fallbacks. When adding another model with
stream_entry in future, consider to update uri_for and url_for.

* Cover TagManager more

ref: #3538 ("Extended information" -> "About this instance") and #3519

Signed-off-by: lindwurm <lindwurm.q@gmail.com>

* Do not default the format in ProviderDiscovery

The format should be determined when discovering, as it is in the current
implementation, and it is a flaw if it is not determined.

* Spec ProviderDiscovery

* Remove some arguments of Formatter.instance.format

* Improve spec for Formatter

* Add Japanese translations (pin)

* "ピン留め" is more general

This change follows #3519, which does the same for the Chinese variants. Or should it be simply "About"?

* Allow mounting arbitrary columns

* Refactor column headers, allow pinning/unpinning and moving columns around

* Collapse animation

* Re-introduce scroll to top

* Save column settings properly, do not display pin options in
single-column view, do not display collapse icon if there is
nothing to collapse

* Fix one instance of public timeline being closed closing the stream
Fix back buttons inconsistently sending you back to / even if history exists

* Getting started displays links to columns that are not mounted

* Remove redundant status.reply? in AtomSerializer#object

* Cover AtomSerializer more

* Add redis key "subscribed:timeline:#{account.id}" to indicate active streaming API listeners exists.

* Add endpoint for notification only stream.

* Run PushUpdateWorker only for users uses Streaming API now.

* Move close hander streamTo(Http/Ws) -> stream(Http/Ws)End (Deal with #3370)

* Add stream type for stream start log message.

* zh-cn.json: "additional info" -> "more info"

This commit changes the "extended info" (about/more) text to something that translates to "more info", as "additional info" in zh can sound like appending things to the (ugh) navbar, I guess.

Or should I just change it to "about this site" (关于本站)?

* zh-cn.json: navbar.info -> "about this site"

* zh-臺灣.json: navbar.info -> "about this site"

WarmCacheService is no longer used (removed with 5442083b3c ).

This fixes #2375.

Used by Intellij IDEA / WebStorm / RubyMine.

Remove protect_from_forgery in ApiController, which is disabled by the
following skip_before_action, as well.

This implementation is a bit smaller and still has the following benefits:

* No need of app/javascript/packs/custom.js
For custom stylesheet, it typically has only
"require('../styles/custom.scss')" and is redundant.

* No need to extract vendor stylesheet to another asset
Extracting vendor stylesheet could be forgotten by developers who do not
use custom stylesheet.

* Update rails to version 5.1.1

* Run `rails app:update`

* Remove the override of polymorphic activity relationship

* Silence warning about otp_secret attribute being unknown to rails

* We will only introduce form_with where we want to use remote data

Needed since merge of #3067.

- Upgrade dependencies
    - chai (3.5.0 -> 4.0.1)
    - chai-enzyme (0.6.1 -> 0.7.1)
    - sinon (2.2.0 -> 2.3.2)
- Change extensions from .jsx to .js
- Don't assign `React` to `global`
- Check code format using ESLint