* Add <ostatus:conversation /> tag to Atom input/output

Only uses ref attribute (not href) because href would be
the alternate link that's always included also.

Creates new conversation for every non-reply status. Carries
over conversation for every reply. Keeps remote URIs verbatim,
generates local URIs on the fly like the rest of them.

* Conversation muting - prevents notifications that reference a conversation
(including replies, favourites, reblogs) from being created. API endpoints
/api/v1/statuses/:id/mute and /api/v1/statuses/:id/unmute

Currently no way to tell when a status/conversation is muted, so the web UI
only has a "disable notifications" button, doesn't work as a toggle

* Display "Dismiss notifications" on all statuses in notifications column, not just own

* Add "muted" as a boolean attribute on statuses JSON

For now always false on contained reblogs, since it's only relevant for
statuses returned from the notifications endpoint, which are not nested

Remove "Disable notifications" from detailed status view, since it's
only relevant in the notifications column

* Up max class length

* Remove pending test for conversation mute

* Add tests, clean up

* Rename to "mute conversation" and "unmute conversation"

* Raise validation error when trying to mute/unmute status without conversation

* Normalize locales

* Restore "mention" locale key

* Add Japanese tranlsation for getting started, and run manage:tranlation

* remove unnecessary {apps}

* package.json: Add "build:*" targets

* Improve react-intl-translations-manager workflow.
  * Added "build:production" to build production bundle.
  * Added "build:development" to build development bundle.

* Fix json translation files

* Run `yarn manage:translations` to fix translation files.
* Fix `pl.json` for syntax error.

* translationRunner: auto detect existing languages

* Auto detect existing rfc5646 language tag in *.json filenames
  in `app/javascript/mastodon/locale` folder. No need to manually
  define every new language in the languages array here.

* translationRunner: add more functionality

* Allow script user to specify language code to check.
* Added available language check.
* Added --force flag to force creation of unexists language.
* Added --help flag and help messages.

* gitignore: ignore npm-debug.log

* Fix webpack error if NODE_ENV is not defined

Default to use 'development' in config/webpack/configuration.js

Signed-off-by: Marcin Mikołajczak <m4sk1n@vivaldi.net>