Updating .gitignore file
Refactoring to structure of ImageLoader
Bugfix: not set NSData to cache
Fixing protocol's interface
- input NSURL
- output NSData?
Fixing logic about UIImageView's completion handler

Reference:
https://github.com/hirohisa/ImageLoader
Adding the queue for managing that task resume/suspend
Adding class Block, has `CompletionHandler`
Adding logic to remove block
- changing to set block in UIImageView from assign to retain nonatomic
- blocks clear when loader comlete
Removing undefine file from project
Adding to cancel requesting task
Renaming store class
Merge pull request #2 from hirohisa/0.1.0

0.1.0