Convert CommonJS exports to ES6-compatible exports

We use `export default` begrudgingly here. Ideally we'd use just `export`, though this entire SDK expects things to be exported as a default. Instead of breaking everything, we'll sacrifice our export pattern for a smaller diff - a later commit can always do the default export -> regular export conversion.

src/components/structures/RoomView.js

@@ -72,7 +72,7 @@ const RoomContext = PropTypes.shape({
     room: PropTypes.instanceOf(Room),
 });
 
-module.exports = createReactClass({
+export default createReactClass({
     displayName: 'RoomView',
     propTypes: {
         ConferenceHandler: PropTypes.any,