change cocos2d-js download url
correct debug lua url
Merge pull request #259 from honghui/master

correct urls
[Cocos2d-JS] Add js about docs
Merge pull request #261 from pandamicro/master

[Cocos2d-JS] Add js about docs
add note for jdk and ide version
[Cocos2d-JS] Improve inheritance doc
Merge pull request #262 from honghui/master

add note for jdk and ide version
Merge pull request #263 from pandamicro/master

[Cocos2d-JS] Improve inheritance doc
Merge pull request #4 from chukong/master

merge the official update