Fix a typo.

modules/UI/UI.js

     if (config.useNicks) {
         nick = window.prompt('Your nickname (optional)');
     }
-    xmpp.joinRooom(roomName, config.useNicks, nick);
+    xmpp.joinRoom(roomName, config.useNicks, nick);
 }
 
 

modules/xmpp/xmpp.js

     promptLogin: function () {
         UI.showLoginPopup(connect);
     },
-    joinRooom: function(roomName, useNicks, nick)
+    joinRoom: function(roomName, useNicks, nick)
     {
         var roomjid;
         roomjid = roomName;