Issue #3427: cc.eventManager supports keyboard events
Issue #3427: remove some unused codes from cc.inputManager
Merge branch 'develop-3.0' of https://github.com/cocos2d/cocos2d-html5 into Iss3427_NewEventDispatcher
Merge pull request #1602 from dingpinglv/Iss3427_NewEventDispatcher

Issue #3427: cc.eventManager supports keyboard events