Fix orientation changes not work under iOS6.  In iOS6, modal view controller will not receive willAnimateRotationToInterfaceOrientation:duration: notification when orientation changed. Instead UIDeviceOrientationDidChangeNotification is used to track the orientation changed.  Tested only both iOS 5 and iOS 6 without problem.
Fix orientation changes not work under iOS6.  In iOS6, modal view controller
will not receive willAnimateRotationToInterfaceOrientation:duration: notification
when orientation changed. Instead UIDeviceOrientationDidChangeNotification is
used to track the orientation changed.  Tested only both iOS 5 and iOS 6 without
problem.

haiwen/REComposeViewController,takeshineshiro/REComposeViewController,kolyvan/REComposeViewController,romaonthego/REComposeViewController