Modified to use keyframe animation
Modified to use keyframe animation

Also the completion block now passed the cancellation from the transition context.

ColinEberhardt/VCTransitionsLibrary,stevenchan/VCTransitionsLibrary,AlexanderMazaletskiy/VCTransitionsLibrary,shaohung001/VCTransitionsLibrary,bb-coder/VCTransitionsLibrary,sunyazhou13/VCTransitionsLibrary,ArkadiYoskovitz/VCTransitionsLibrary,hugo-/VCTransitionsLibrary,csjlengxiang/VCTransitionsLibrary,leonardlee2015/VCTransitionsLibrary,junjie/VCTransitionsLibrary,cnbin/VCTransitionsLibrary,HarrisLee/VCTransitionsLibrary,xxbinxx/VCTransitionsLibrary,ganvinalix/VCTransitionsLibrary