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/groups/index/card.js

@@ -1,10 +1,8 @@
-import React from 'react';
 import ImmutablePropTypes from 'react-immutable-proptypes';
 import ImmutablePureComponent from 'react-immutable-pure-component';
 import { defineMessages, injectIntl } from 'react-intl';
 import { Link } from 'react-router-dom';
 import { shortNumberFormat } from '../../../utils/numbers';
-import { connect } from 'react-redux';
 
 const messages = defineMessages({
     members: { id: 'groups.card.members', defaultMessage: 'Members' },