Add some sanity check on the URL parameter

Merge pull request SDWebImage#221 from JaviSoto/master

CRASH: Fixing overrelease of UIImage object

Revert "Fixed Alpha chanel detection when decoding images."

This reverts commit e6ede11.

Fix SDWebImage#200 crash on archived builds

Switch to framework distribution

Add a cached parameter to the success block to tell the receiver if t…

…he image came from cache or network SDWebImage#181

Do not check request response status code when the protocol isn't HTTP (

fix SDWebImage#110)

Fix a bug in SDImageCache making first request to disk cache to alway…

…s return nil (fix SDWebImage#81)

Failsafe a very common usage error (passing URL as NSString instead o…

…f NSURL)

Perform disk cache out operations asynchronousely in order to prevent…

… from blocking the main runloop when a lot of cache queries are performed at the same time