Added webpack.ProvidePlugin for most used imports

Removed imports of React, connect, PropTypes throughout
Removed the "React" in React.Component/PureComponent

app/javascript/gabsocial/features/home_timeline/components/column_settings.js

@@ -1,11 +1,9 @@
-import React from 'react';
-import PropTypes from 'prop-types';
 import ImmutablePropTypes from 'react-immutable-proptypes';
 import { injectIntl, FormattedMessage } from 'react-intl';
 import SettingToggle from '../../notifications/components/setting_toggle';
 
 export default @injectIntl
-class ColumnSettings extends React.PureComponent {
+class ColumnSettings extends PureComponent {
 
   static propTypes = {
     settings: ImmutablePropTypes.map.isRequired,