Update README.md
Fix crash when menu view controller is being set to nil, close #28
Fix crash when menu view controller is not assigned, close #29
Add REFrostedViewControllerDelegate to handle notifications, close #33
Add ability to disable pan gesture, close #31
Expose pan gesture recognizer, close #32
Add note about live blur and iOS 7
Fix deprecation warning
Improve menu view size support, close #27
Add willAnimateRotationToInterfaceOrientation to delegate