IOS : Allow rotation and display button for rotate

[yucomds]

Hi,

I wander if it's possible to make the cropController.rotationEnabled as a config option instead of hardcode NO as it's value.

In addition, I wander if it's possible to add a button for 90degree rotation.

I saw in PEPhotoCropEditor library the method setRotationAngle for the programmatic rotation, so I think should't be difficult to add a shortcut button on the interface.

What do you think?