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/components/attachment_list.js

@@ -0,0 +1,33 @@
+import React from 'react';
+import ImmutablePropTypes from 'react-immutable-proptypes';
+
+const filename = url => url.split('/').pop().split('#')[0].split('?')[0];
+
+class AttachmentList extends React.PureComponent {
+
+  render () {
+    const { media } = this.props;
+
+    return (
+      <div className='attachment-list'>
+        <div className='attachment-list__icon'>
+          <i className='fa fa-link' />
+        </div>
+
+        <ul className='attachment-list__list'>
+          {media.map(attachment =>
+            <li key={attachment.get('id')}>
+              <a href={attachment.get('remote_url')} target='_blank' rel='noopener'>{filename(attachment.get('remote_url'))}</a>
+            </li>
+          )}
+        </ul>
+      </div>
+    );
+  }
+}
+
+AttachmentList.propTypes = {
+  media: ImmutablePropTypes.list.isRequired
+};
+
+export default AttachmentList;