Add rule to enforce spacing in curly brackets in JSX children

This required an updated in version of eslint-plugin-react to 7.4.0.

src/components/views/rooms/ForwardMessage.js

@@ -61,7 +61,7 @@ module.exports = React.createClass({
     render: function() {
         return (
             <div className="mx_ForwardMessage">
-                <h1>{_t('Please select the destination room for this message')}</h1>
+                <h1>{ _t('Please select the destination room for this message') }</h1>
             </div>
         );
     },