Merge pull request #285 from dingpinglv/Iss4887_MouseMove

Fixed #4887: Modify cc.inputManager's mouseMove event that its button needn't pressed
Fixed #4887: Modify cc.inputManager's mouseMove event that its button needn't pressed
Merge branch 'master' of https://github.com/cocos2d/cocos2d-js into Iss4887_MouseMove