Added UIImage category to apply noise to any image
Added a UIColor category
Make sure both categories play nice with Retina displays
Added a mask to the image category
Merge https://github.com/Vortec4800/KGNoise into Vortec4800
Added the image noise categories to the main KGNoise file so there is only one thing to add. Also implemented the image category for NSImage and added examples to the sample apps.

fix #2