cocos2d v3 fixed size screen mode

// Use v3's new fixed size screen mode to make it easier to support multiple device scales and resolutions.
// It sets up Cocos2D with a 568x384 point "design size".
// On iPhone 4 you see the middle 480x320 of it and the rest is cropped.
// On iPhone 5 you see the middle 568x320 of it.
// On iPad you see the middle 512x384 of that. (It sets the iPad's content scale to 2 or 4 for retina)
CCSetupScreenMode: CCScreenModeFixed,