Merge pull request #1686 from pandamicro/develop-3.0

Refactor #4365: Refactor layers and sprite constructors with init functionality
Fixed #4277: fixed a bug that UILoadingBar doesn't work on Scale9Sprite
Merge branch 'develop-3.0' of git://github.com/cocos2d/cocos2d-html5 into Iss4277_ReleaseV3.0
Merge pull request #1687 from dingpinglv/Iss4277_ReleaseV3.0

Fixed #4277: fixed a bug that UILoadingBar doesn't work on Scale9Sprite
Refactor #4365: Improve layers constructors
Refactor #4365: Refactor SpriteBatchNode constructor with init functionality
Refactor #4365: Refactor Menu and MenuItems constructor with init functionality
Merge branch '4365ctor' into develop-3.0