API update.
Use 404.html from html5-boilerplate

Use Google fixurl service to provide suggestions and search box.

refs http://ruby-china.org/topics/7960
reproduce #63
use attr to fetch string may having leading zero
Fix name starting with leading zero when scan logins
refactor the code to scan logins
Do not init faye when user has not logged in.

The Javascript error can block js execution in Firefox, and lead to bug
like #135
fixed faye config

fixed faye config
Merge pull request #141 from doitian/bug/135-js-error-block-execution-in-firefox

Do not init faye when user has not logged in.
Merge pull request #142 from huxinghai1988/patch-1

fixed faye config
merge.
Merge branch 'enhancement/html5-boilerplate-404' of git://github.com/doitian/ruby-china into doitian-enhancement/html5-boilerplate-404
Update 404, 500 page content.
Add test cases to cover the formatting bugs
Fix emoji, user/floor metion in code/pre
Fix underscores in user metion
Add rake task markdown_body:refresh to fix existing invalid HTML body
replace username with place holder to avoid markdown emphasis
fix private method `image_alt` in markdown.rb
Test @small_fish__ in highlighted ruby code block