Update JBKenBurnsView.m

Warning: Implicit conversion from enumeration type 'enum UIViewAnimationCurve' to different enumeration type 'UIViewAnimationOptions' (aka 'enum UIViewAnimationOptions').

UIViewAnimationCurveEaseOut => UIViewAnimationOptionCurveEaseOut
Merge pull request #25 from alexllao/patch-1

Update JBKenBurnsView.m (UIViewAnimationOptionCurveEaseOut)