Merge pull request #1030 from dingpinglv/Iss2362_AddLogToSchedule

Fixed 2362 Add a log to notice that schedule parameters can't end with "null"
fixed #2293 fixed a bug of cc.LabelTTF when its stroke or shadow enables on WebGL Mode
Merge branch 'develop' of https://github.com/cocos2d/cocos2d-html5 into Iss2362_AddLogToSchedule