Merge pull request #9 from cocos2d/develop

pull down
Fixed #3461 : Fix patch to CCLabelTTF
Fixed #3461 : Change to real class static properties

_measureCanvas and _measureCtx now is real class static properties,
then can be accessed with cc.LabelTTF._measureCanvas
Merge pull request #1342 from pandamicro/develop

Fixed #3461 : Fix patch to CCLabelTTF