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/features/compose/containers/sensitive_button_container.js

@@ -0,0 +1,51 @@
+import React from 'react';
+import { connect } from 'react-redux';
+import PropTypes from 'prop-types';
+import TextIconButton from '../components/text_icon_button';
+import { changeComposeSensitivity } from '../../../actions/compose';
+import { Motion, spring } from 'react-motion';
+import { injectIntl, defineMessages } from 'react-intl';
+
+const messages = defineMessages({
+  title: { id: 'compose_form.sensitive', defaultMessage: 'Mark media as sensitive' }
+});
+
+const mapStateToProps = state => ({
+  visible: state.getIn(['compose', 'media_attachments']).size > 0,
+  active: state.getIn(['compose', 'sensitive'])
+});
+
+const mapDispatchToProps = dispatch => ({
+
+  onClick () {
+    dispatch(changeComposeSensitivity());
+  }
+
+});
+
+class SensitiveButton extends React.PureComponent {
+
+  render () {
+    const { visible, active, onClick, intl } = this.props;
+
+    return (
+      <Motion defaultStyle={{ scale: 0.87 }} style={{ scale: spring(visible ? 1 : 0.87, { stiffness: 200, damping: 3 }) }}>
+        {({ scale }) =>
+          <div style={{ display: visible ? 'block' : 'none', transform: `translateZ(0) scale(${scale})` }}>
+            <TextIconButton onClick={onClick} label='NSFW' title={intl.formatMessage(messages.title)} active={active} />
+          </div>
+        }
+      </Motion>
+    );
+  }
+
+}
+
+SensitiveButton.propTypes = {
+  visible: PropTypes.bool,
+  active: PropTypes.bool,
+  onClick: PropTypes.func.isRequired,
+  intl: PropTypes.object.isRequired
+};
+
+export default connect(mapStateToProps, mapDispatchToProps)(injectIntl(SensitiveButton));