Retina support WIP
Retina WIP
Merge remote-tracking branch 'apportable/develop' into retina

Conflicts:
	SpriteBuilder/SpriteBuilder.xcodeproj/project.pbxproj
Retina support for CocosView
Determine backing scale dynamically
Update cocos2d-swift to retina branch
Update to latest cocos2d
Merge remote-tracking branch 'apportable/develop' into retina
Merge pull request #1206 from stuartcarnie/retina

Retina support