Closed #2748: Fix a bug of cc.Sprite that its children also follow fliped when it fliped
Closed #2748: Fixed a bug of LabelAtlasCanvas, that   _opacity is wrong used.
Closed #2748: Fixed a bug of cc.ProgressTimerCanvas that it is error display  when it flip.
closed #2748: clipping region also must use   save and  restore
Merge pull request #1112 from xingsenma/Flip

closed #2748: Fixed some bugs about flip.