fixed #1944: The subclass of cc.Sprite,cc.Layer... doesn't need cc.associateWithNative anymore.
Merge branch 'master' of https://github.com/cocos2d/cocos2d-x into iss1944-remove-associate-nativeobj
issue #1944: Removing commented codes in cc.associateWithNative.
issue #1944: Fixing a typo.
Merge pull request #2291 from dumganhar/iss1944-remove-associate-nativeobj

fixed #1944: The subclass of cc.Sprite,cc.Layer... doesn't need cc.associateWithNative anymore.