Replace sprockets/browserify with Webpack (#2617)

* 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

app/javascript/mastodon/reducers/settings.js

@@ -0,0 +1,52 @@
+import { SETTING_CHANGE } from '../actions/settings';
+import { STORE_HYDRATE } from '../actions/store';
+import Immutable from 'immutable';
+
+const initialState = Immutable.Map({
+  onboarded: false,
+
+  home: Immutable.Map({
+    shows: Immutable.Map({
+      reblog: true,
+      reply: true
+    }),
+
+    regex: Immutable.Map({
+      body: ''
+    })
+  }),
+
+  notifications: Immutable.Map({
+    alerts: Immutable.Map({
+      follow: true,
+      favourite: true,
+      reblog: true,
+      mention: true
+    }),
+
+    shows: Immutable.Map({
+      follow: true,
+      favourite: true,
+      reblog: true,
+      mention: true
+    }),
+
+    sounds: Immutable.Map({
+      follow: true,
+      favourite: true,
+      reblog: true,
+      mention: true
+    })
+  })
+});
+
+export default function settings(state = initialState, action) {
+  switch(action.type) {
+  case STORE_HYDRATE:
+    return state.mergeDeep(action.state.get('settings'));
+  case SETTING_CHANGE:
+    return state.setIn(action.key, action.value);
+  default:
+    return state;
+  }
+};