Allow iOS orientation changes when returning to libgdx game's ViewController

Add override for getSupportedInterfaceOrientations() and shouldAutorotate() to IOSUIViewController in robovm backend to ensure that any time a user returns to the libgdx game, the rotation is set correctly based on the settigs in the libgdx config object.

Allow LandscapeLeft and LandscapeRight for "landscape" orientation. Allow Portrait and PortraitUpsideDown for "portrait" orientation. May want to consider removing the PortraitUpsideDown, depending on community preferences.

Reference my forum post: http://www.badlogicgames.com/forum/viewtopic.php?f=11&t=14211