Adding webpack code splitting (#3377)

webapp/components/password_reset_send_link.jsx

@@ -9,7 +9,7 @@ import client from 'utils/web_client.jsx';
 import {FormattedMessage, FormattedHTMLMessage} from 'react-intl';
 
 import React from 'react';
-import {Link} from 'react-router';
+import {Link} from 'react-router/es6';
 
 class PasswordResetSendLink extends React.Component {
     constructor(props) {