Merge pull request #673 from pandamicro/master

Fix issues and add cc.sys.platfom
Fixed #5781: update build.xml of MoonWarriors
Merge branch 'master' of https://github.com/cocos2d/cocos2d-js into Iss5781_V3rc2
Merge pull request #677 from dingpinglv/Iss5781_V3rc2

Fixed #5781: update build.xml of MoonWarriors
Merge branch 'master' of https://github.com/cocos2d/cocos2d-js