Merge pull request #14 from antoinerabanes/master

show placeholder if downloaded data is not an image
Fixing .podspec file.
Bumping versionto 0.0.4
Ugh bumping version for Cocoapods.
Call removeObjectForKey: on ourselves instead of super to accomplish removing from disk as well as in-memory cache. Fixes #15.
Added Default images to Demo app. Improved image loading behavior. Added a note about the call to removeAllObjects in the init method of DemoViewController.
More cleanup, removing DemoTableViewCell and updating .podspec file.
adding completion block to UIImageView category
Merge pull request #16 from atomkirk/master

Added completion block to UIImageView category
Added failureBlock to allow proper handing of errors situations
Initialize JMImageCacheDirectory and sharedCache atomically
Fixed declaration to match implementation.
Merge pull request #20 from gwagener/master

Fixed declaration to match implementation
Merge pull request #18 from jlnr/master

Initialize static variables atomically
Merge pull request #17 from Brendtos/master

failureBlock
Fix for infinite recursion issue caused by missing call parameter of failureBlock