Have the Fullscreen service $broadcast fullscreen.changed events on the $rootscope

I found it easiest to move this logic out of directives and controllers and into the one service.  The namespace + name of the event is unimportant.
[This Plunker](http://plnkr.co/edit/RfRhefWWlRWTJ2rczBvg?p=preview), shows it in action, and you can test it by launching Plunker's separate window.