Merge pull request #181 from dumganhar/master

Updates cocos2d-x
update submodule
Merge pull request #182 from lihex/master

update submodule
Closed #4277: update README.md
Merge branch 'master' of https://github.com/cocos2d/cocos2d-js into Iss4277_ReleaseV3.0
Merge pull request #183 from dingpinglv/Iss4277_ReleaseV3.0

Closed #4277: update README.md
Updates cocos2d-x