Merge branch 'develop' of https://github.com/cocos2d-x/plugin-x into fb
Merge pull request #3 from wuzhiming/plugin_fb_4th

Plugin fb 4th
Refactor #5900 : Refactor all plugin-x's constant name to UPPERCASE
issue #5901: Move FacebookAgent's getSDKVersion to FacebookAgent.h and add bindings for it, publishInstall -> activateApp
Merge pull request #6 from joshuastray/fb

Fb