Closed #5832: fixed a bug of RenderTexture that it doesn't support depthStencilFormat
Merge branch 'develop' of git://github.com/cocos2d/cocos2d-html5 into Iss5832_RenderTexture
Merge pull request #2141 from dingpinglv/Iss5832_RenderTexture

Closed #5832: fixed a bug of RenderTexture that it doesn't support depthStencilFormat