Fix removing the name of the room

The name of the room is removed by setting it to the empty string, but
the if condition was wrong and thus an empty string did not satisfy it.

Signed-off-by: Daniel Calviño Sánchez <danxuliu@gmail.com>

js/models/room.js

@@ -67,7 +67,7 @@
 			// Moreover, the endpoint to rename a room expects the name to be
 			// provided in a "roomName" attribute instead of a "name"
 			// attribute, so that has to be changed too.
-			if (method === 'patch' && options.attrs.name) {
+			if (method === 'patch' && options.attrs.name !== undefined) {
 				method = 'update';
 
 				options.attrs.roomName = options.attrs.name;