* Redirect to streaming_api_base_url

When Rails receives a request to streaming API, it most likely
means that there is another host which is configured to respond
to it. This is to redirect clients to that host if
`STREAMING_API_BASE_URL` is set as another host.

* Use the new Ruby 1.9 hash syntax

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

* Added support for configurable reserved usernames

* Added reserved usernames from mastodon issue 1355

* Fix reserved usernames

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

Since 6d6a429a, 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

* 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

* Remove redundant status.reply? in AtomSerializer#object

* Cover AtomSerializer more

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

- 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

* Add failing specs for hashtag and username extraction in language detector

* Remove usernames and hashtags from text before language detection

* Handle multiple instances of special case, and reduce whitespace

* Move specs for account finder methods to concern spec

* Move account finder methods to concern

* Improve spec wording

* Use more explicit comparison to ensure correct return value

* Add coverage for .find_local! and .find_remote!

* Add some methods to the finder

* Use arel on matching_username method

* Avoid ternary in matching domain method

* Simplify finder methods

* Use an AccountFinder class to simplify lookup

* Keep ENV['LOCAL_HTTPS'] with ApplicationControllerSpec (fix random fail)

* use climate_control

* Add status destroy authorization to policy

* Create explicit unreblog status authorization

* Add StreamEntryFinder class to parse URLs

* Use StreamEntryFinder and clean up api/oembed controller

* Protect send_devise_notification of User

* Improve spec for User