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/packs/public.js

@@ -0,0 +1,53 @@
+import emojify from 'mastodon/emoji';
+import { length } from 'stringz';
+
+window.jQuery = window.$ = require('jquery');
+require('jquery-ujs');
+require.context('../images/', true);
+
+$(() => {
+  $.each($('.emojify'), (_, content) => {
+    const $content = $(content);
+    $content.html(emojify($content.html()));
+  });
+
+  $('.video-player video').on('click', e => {
+    if (e.target.paused) {
+      e.target.play();
+    } else {
+      e.target.pause();
+    }
+  });
+
+  $('.media-spoiler').on('click', e => {
+    $(e.target).hide();
+  });
+
+  $('.webapp-btn').on('click', e => {
+    if (e.button === 0) {
+      e.preventDefault();
+      window.location.href = $(e.target).attr('href');
+    }
+  });
+
+  $('.status__content__spoiler-link').on('click', e => {
+    e.preventDefault();
+    const contentEl = $(e.target).parent().parent().find('div');
+
+    if (contentEl.is(':visible')) {
+      contentEl.hide();
+      $(e.target).parent().attr('style', 'margin-bottom: 0');
+    } else {
+      contentEl.show();
+      $(e.target).parent().attr('style', null);
+    }
+  });
+
+  $('.account_display_name').on('input', e => {
+    $('.name-counter').text(30 - length($(e.target).val()));
+  });
+
+  $('.account_note').on('input', e => {
+    $('.note-counter').text(160 - length($(e.target).val()));
+  });
+});