Adding webpack code splitting (#3377)

webapp/components/tutorial/tutorial_intro_screens.jsx

@@ -10,7 +10,7 @@ import * as GlobalActions from 'actions/global_actions.jsx';
 import Constants from 'utils/constants.jsx';
 
 import {FormattedMessage, FormattedHTMLMessage} from 'react-intl';
-import {browserHistory} from 'react-router';
+import {browserHistory} from 'react-router/es6';
 
 const Preferences = Constants.Preferences;