Make ParticipantCollection to automatically fetch when its room changes

The ParticipantCollection provides the list of participants (including
guests) in a room. The Room model is synced through signaling and
provides some information about the registered users and the guests in a
room, so the ParticipantCollection can listen to changes in those
properties to automatically fetch its items again when needed.

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

js/models/participantcollection.js

@@ -35,8 +35,20 @@
 		 * @returns {Array}
 		 */
 		setRoom: function(room) {
+			this.stopListening(this.room, 'change:participants');
+			this.stopListening(this.room, 'change:guestList');
+
 			this.room = room;
 			this.url = OC.linkToOCS('apps/spreed/api/v1/room', 2) + this.room.get('token') + '/participants';
+
+			this.fetch();
+
+			this.listenTo(this.room, 'change:participants', function() {
+				this.fetch();
+			});
+			this.listenTo(this.room, 'change:guestList', function() {
+				this.fetch();
+			});
 		},
 
 		/**

js/views/roomlistview.js

@@ -185,7 +185,6 @@
 			$sidebar.find('.room-name').text(this.model.get('displayName'));
 
 			OCA.SpreedMe.app._participants.setRoom(this.model);
-			OCA.SpreedMe.app._participants.fetch();
 
 			if (!$content.hasClass('with-app-sidebar')) {
 				$content.addClass('with-app-sidebar');