Big image decompression

If you library open big jpeg files. It hang UI.

so i would like to suggest:
1. open file in background thread
2. decompress file in background thread
     http://orion98mc.blogspot.ru/2012/08/on-ios-uiimage-decompression-nightmare.html
3. return image in block on main thread

ps your library is very good but it miss this two important things. Thank you for your code)
