Use ES Class Fields & Static Properties (currently stage 2) for improve class outlook.

Added babel-plugin-transform-class-properties as a Babel plugin.

* Fix regressions from #2683

Properly format spoiler text HTML, while keeping old logic for blankness intact
Process hashtags and mentions in spoiler text
Format spoiler text for Atom
Change "show more" toggle into a button instead of anchor
Fix style regression on dropdowns for detailed statuses

* Fix lint issue

* Convert spoiler text to plaintext in desktop notifications

* Replace browserify with webpack

* Add react-intl-translations-manager

* Do not minify in development, add offline-plugin for ServiceWorker background cache updates

* Adjust tests and dependencies

* Fix production deployments

* Fix tests

* More optimizations

* Improve travis cache for npm stuff

* Re-run travis

* Add back support for custom.scss as before

* Remove offline-plugin and babili

* Fix issue with Immutable.List().unshift(...values) not working as expected

* Make travis load schema instead of running all migrations in sequence

* Fix missing React import in WarningContainer. Optimize rendering performance by using ImmutablePureComponent instead of
React.PureComponent. ImmutablePureComponent uses Immutable.is() to compare props. Replace dynamic callback bindings in
<UI />

* Add react definitions to places that use JSX

* Add Procfile.dev for running rails, webpack and streaming API at the same time

* fix(classnames): Status icon style classnames

Take out inline css and put into classnames for the following components: account, avatar, icon button, status action bar, notification.

* fix(status): Move styles from inline to classes for statuses

Move styles to classnames in components.scss for the following components:

display name
media gallery
status
status content
video player

* fix(classnames): Add classnames to rest of components

Take out inline styles and apply them to classnames in the sass for the following components:

button
column back button
slim column back button
collapsable column
dropdown menu
loading indicator
status list

* fix(classnames): Remove all non-dynamic inline styles

Components affected:

autosuggested
permalink
action bar
header
character counter
compose form
emoji dropdown
privacy dropdown
reply indicator
upload form
account auth
followers
getting started
column settings
mutes
settings
reblogs
status checkbox
report
action bar
status
card
boost modal
media modal
video modal

* fix(permalink): Do not lose classname

* fix(tests): Add space back in display name

* fix(status__wrapper): Remove duplicate css name

Remove incorrect style attribute. Remove style attribute all together. Cursor defaults to "auto" when not specified as 'default'.

* fix(nl): do not lose translations

* Remove deprecated features at React v15.5

- [x] React.PropTypes
- [x] react-addons-pure-render-mixin
- [x] react-addons-test-utils

* Uncommented out & Add browserify_rails options

* re-add react-addons-shallow

* Fix syntax error from resolve conflicts

* follow up 59a77923b3

* Add eslint-plugin-jsx-a11y.

* Fix npm script.

* Adjust npm scripts so test also runs lint.

* Fix existing lint errors.

* Don't break on a11y issues.

* Add role and tabIndex.

* Add vim and Mac files to .gitignore and .dockerignore.

* Handle htmlFor (partially), a that's actually a button.

* Fix missing tabIndex.

* Add cursor:pointer to load-more

* Revert change to load_more.

* Fixes based on review.

* Update yarn.lock.

* Don't try to install fsevents on Linux (hides warning noise).

Since URLs in statuses are truncated, it would be pleasant to see the
full URL when hovering the URL (like on twitter, yes).

When transmitting data in a HTML-encoded element like <content type="html" />,
relying on newlines being preserved is not wise, since HTML by itself
does not care for newlines - it cares for <p> and <br>

Additional fix: reset NSFW toggle after sending toot

Add a title attribute on mention links for both notifications
and mentions in statuses.

Related to #1350

warning mentions preview into area where actual content would be

untested, my vagrant is bugged again, submitted at gargron's request

fix ProcessFeedService pushing status into distribution if called a second time
while the first is still running (i.e. when a PuSH comes after a Salmon slap),
fix not running escape on spoiler text before emojify

improved how "show more" link looks

Federate spoiler_text using warning attribute on <content /> instead of a <category term="spoiler" />
Clean up schema file from accidental development migrations

affected, replaced onClick handler with onMouseUp/Down to detect text
selection not trigger onClick handler then

status clickable (this also fixes multiple dropdown being openable at the same
time)

Track relationship in redux state. Display follow/unfollow and following-back
information on account view (unstyled)