Added webpack.ProvidePlugin for most used imports

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

app/javascript/gabsocial/containers/dropdown_menu_container.js

@@ -1,6 +1,5 @@
 import { openDropdownMenu, closeDropdownMenu } from '../actions/dropdown_menu';
 import { openModal, closeModal } from '../actions/modal';
-import { connect } from 'react-redux';
 import DropdownMenu from '../components/dropdown_menu';
 import { isUserTouching } from '../utils/is_mobile';