crop image with path
added comments. I try to be a good citizen. But honestly: I feel like an idiot commenting methods that pretty much have self-explaining names.
UIGraphicsBeginImageContextWithOptions
flip Core Graphics coordinate system so that the coordinates for the UIImage and the UIBezierPath match
but of course we want to flip back the image.
removed dead code
now in retina quality
create bitmap contexts  w/ retina scaling
Merge pull request #1 from vikingosegundo/master

cropping with paths and grayscale conversion for UIImage