change API name from cc.Control.removeTargetWithActionForControlEvent to _removeTargetWithActionForControlEvent

change API name from cc.Control.removeTargetWithActionForControlEvent to _removeTargetWithActionForControlEvent

1、In my opinion , API name should be symmetrical , such as _addTarget and _removeTarget
2、removeTargetWithActionForControlEvent is a protected function in cocos2d-x , so it should be add "_" prefix in cocos2d-html5 such as _addTargetWithActionForControlEvent