Sync room state when joining via client.joinRoom

Does not currently sync state when another device joins.
Update node example app to refresh room list.

lib/models/room.js

@@ -55,6 +55,18 @@ utils.inherits(Room, EventEmitter);
     });
  };
 
+ /**
+ * Check if the given user_id has the given membership state.
+ * @param {string} userId The user ID to check.
+ * @param {string} membership The membership e.g. <code>'join'</code>
+ * @return {boolean} True if this user_id has the given membership state.
+ */
+ Room.prototype.hasMembershipState = function(userId, membership) {
+    return utils.filter(this.currentState.getMembers(), function(m) {
+        return m.membership === membership && m.userId === userId;
+    }).length > 0;
+ };
+
 /**
  * Add some events to this room's timeline. Will fire "Room.timeline" for
  * each event added.