Added webpack.ProvidePlugin for most used imports

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

app/javascript/gabsocial/components/scrollable_list.js

@@ -1,5 +1,4 @@
 import React, { PureComponent } from 'react';
-import PropTypes from 'prop-types';
 import IntersectionObserverArticleContainer from '../containers/intersection_observer_article_container';
 import LoadMore from './load_more';
 import IntersectionObserverWrapper from '../features/ui/util/intersection_observer_wrapper';