add Linux in README.md
Merge pull request #641 from joshuastray/master

add Linux in README.md
Merge pull request #642 from pandamicro/master

Issue #5742: Add js_load_remote_image for load a image url to a texture in js
Issue #5781: Clean up game start up code
Update plugin-x ref for FacebookAgent
Fixed #5760: Improve templates HelloWorld project
Merge branch 'master' of https://github.com/cocos2d/cocos2d-js