Fixed issue 204: center view gets truncated if user holds finger on the screen during the device rotation.

See https://github.com/mutualmobile/MMDrawerController/issues/204 for reference

Fix description:
If user holds a finger on screen during device rotation and once rotation is complete moves a finger panGestureCallback uses outdated value of self.startingPanRect and adjusts center view improperly. So i'm suggesting to refresh this value just after the rotation.