Add language selector to the docs&primary-nav

Add language selector,and change twitter to weibo because we cann’t
visit twitter at china :(
This file should be in the last commit
Remove console.log in view function

There was a console.log in view function to show the
req.session.currentLanguage for debug,not need it anymore.
sync with upstream
Merge remote-tracking branch 'upstream/master'
add "static options" in zh docs
sync docs.js with upstream
sync docs.js with upstream
Merge pull request #806 from wuhaixing/master

Add "static options" in zh docs