Update podspec homepage url
Simplify NSURLRequest creation
Create different cache keys for memory a disk
Fix wrong NSOperation subclass

I don't have a clue why that ended up being a NSOperation subclas...
Refactor UIImageView download to use the manager
Remove LRImageCache singleton. Everything should pass through image manager
Fix image orientation bug #12
Minor refactor about image decompression
Remove LRNetImageBlock and use LRImageCompletionHandler all around for consistency
Handle images with alpha components