fixing eslint errors

web/react/components/mention.jsx

@@ -1,6 +1,7 @@
 // Copyright (c) 2015 Mattermost, Inc. All Rights Reserved.
 // See License.txt for license information.
 var UserStore = require('../stores/user_store.jsx');
+const Utils = require('../utils/utils.jsx');
 
 export default class Mention extends React.Component {
     constructor(props) {