Merge pull request #2131 from dingpinglv/Iss5800_StencilBug

Fixed #5811: cc.Armature supports setting shader program in v2.x
Closed #5832: Fixed a bug of RenderTexture that it doesn't support depthStencilFormat in v2.x
Merge branch 'v2.x' of https://github.com/cocos2d/cocos2d-html5 into Iss5800_StencilBug
Correct a mistake of ccui.Widget.updateSizeAndPosition