Bug 1110832 - When clicking on the notification about someone has joined a room, Room list in Loop should be launched

See bug https://bugzilla.mozilla.org/show_bug.cgi?id=1110832 please. Action happens at https://github.com/jaoo/firefoxos-loop-client/tree/1110832.
https://github.com/mozilla-b2g/firefoxos-loop-client/blob/master/app/js/screens/calllog.js#L1183