Added auto release pool to keep memory foot print down when retrieving image from disk in queryDiskCacheForKey
Merge branch 'master' of github.com:rs/SDWebImage

Conflicts:
	SDWebImage/SDImageCache.m
changed completedBlock() call to pass YES for argument: finished
this fix will to call the secondary completion block in the event that we are not retrying failed urls (which is the default behavior)