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/actions/store.js

@@ -0,0 +1,17 @@
+import Immutable from 'immutable';
+
+export const STORE_HYDRATE = 'STORE_HYDRATE';
+
+const convertState = rawState =>
+  Immutable.fromJS(rawState, (k, v) =>
+    Immutable.Iterable.isIndexed(v) ? v.toList() : v.toMap().mapKeys(x =>
+      Number.isNaN(x * 1) ? x : x * 1));
+
+export function hydrateStore(rawState) {
+  const state = convertState(rawState);
+
+  return {
+    type: STORE_HYDRATE,
+    state
+  };
+};