1.4.1 -> 1.4.2？

Add streaming_api_base_url to /api/v1/instance (#3556)
Fix #3550 - Add all missing foreign keys (#3562)
Redirect to streaming_api_base_url (#3579)
Added support for configurable reserved usernames (fix of #1382) (#3566)
Allow mounting arbitrary columns (#3207) + 大量のUI変更
change sidekiq queueing to bulk push (#3536)
Execute PushUpdateWorker only for accounts who uses StreamingAPI just now. (#3278)
Update Rails to version 5.1.1 (#3121)
Remove usernames and hashtags from language detection (#3503)
[RFC] Return 401 for an authentication error on WebSockets (#3411)
Don't stream toots from users who have blocked the recipient user (#3300)
大量のspec追加とリファクタリング