Check blocks are non-nil before invoking them in imageAtURL
Merge pull request #266 from juliengrimault/master

Check block != nil before invoking them in imageAtURL:completionHandler:errorHandler:
Fixed a EXC-BAD-ACCESS crash
Merge branch 'master' of github.com:MugunthKumar/MKNetworkKit
Renamed a method in a category to avoid conflict with a private api
Added a property that will disable cache on a operation level, added a property to override and cache https urls
Images will be cached even if they are on secure server
Response JSON with options method added to support parsing json fragments
Decompression routines has a bug in retina devices, returns non retina images at times. this was fixed
Merge branch 'master' of https://github.com/MugunthKumar/MKNetworkKit

Conflicts:
	MKNetworkKit/MKNetworkOperation.h
	MKNetworkKit/MKNetworkOperation.m