Merge pull request #235 from pandamicro/master

Update documents for Cocos2d-JS v3.0 alpha 2 release
add release note for rc2
Merge pull request #236 from minggo/release-note-rc2

add release note for rc2
fixes for v3.0_rc2
Merge pull request #237 from ricardoquesada/cocos2d_3_0_rc2

fixes for v3.0_rc2 release notes
[Cocos2d-JS]Update upgrade guide title
Merge branch 'master' of https://github.com/cocos2d/cocos-docs