bugfix: sandstone css download-button
feature: tabzilla add `onReady` and `setStatic`
bugfix: thunderbird `index2.shtml`
issue link on moztw-general:
https://groups.google.com/d/topic/moztw-general/DObvX-z9ljc/48J8iDf-5TYJ
bugfix: thunderbird center the links under dl btn
improve: speed up os_detector.js
update: tabzilla-static.png
improve: update some pic and css
Merge branch 'thunderbird-improve'
bugfix: wrong width setting in css
add hacked info banner
modify alert banner style
point to announcement article on forum
small style fix
Merge remote-tracking branch 'origin/master' into production