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/column_collapsable.js

@@ -0,0 +1,57 @@
+import React from 'react';
+import { Motion, spring } from 'react-motion';
+import PropTypes from 'prop-types';
+
+class ColumnCollapsable extends React.PureComponent {
+
+  constructor (props, context) {
+    super(props, context);
+    this.state = {
+      collapsed: true
+    };
+
+    this.handleToggleCollapsed = this.handleToggleCollapsed.bind(this);
+  }
+
+  handleToggleCollapsed () {
+    const currentState = this.state.collapsed;
+
+    this.setState({ collapsed: !currentState });
+
+    if (!currentState && this.props.onCollapse) {
+      this.props.onCollapse();
+    }
+  }
+
+  render () {
+    const { icon, title, fullHeight, children } = this.props;
+    const { collapsed } = this.state;
+    const collapsedClassName = collapsed ? 'collapsable-collapsed' : 'collapsable';
+
+    return (
+      <div className='column-collapsable'>
+        <div role='button' tabIndex='0' title={`${title}`} className={`column-icon ${collapsedClassName}`} onClick={this.handleToggleCollapsed}>
+          <i className={`fa fa-${icon}`} />
+        </div>
+
+        <Motion defaultStyle={{ opacity: 0, height: 0 }} style={{ opacity: spring(collapsed ? 0 : 100), height: spring(collapsed ? 0 : fullHeight, collapsed ? undefined : { stiffness: 150, damping: 9 }) }}>
+          {({ opacity, height }) =>
+            <div style={{ overflow: height === fullHeight ? 'auto' : 'hidden', height: `${height}px`, opacity: opacity / 100, maxHeight: '70vh' }}>
+              {children}
+            </div>
+          }
+        </Motion>
+      </div>
+    );
+  }
+}
+
+ColumnCollapsable.propTypes = {
+  icon: PropTypes.string.isRequired,
+  title: PropTypes.string,
+  fullHeight: PropTypes.number.isRequired,
+  children: PropTypes.node,
+  onCollapse: PropTypes.func
+};
+
+export default ColumnCollapsable;