add contribute tab 依程式語言選擇
add contribute tab-2 button 新手Bug
global os detector
os detector
Merge pull request #105 from yuan817/master

在contribute新增tab: 依程式語言選擇
css module wider
Merge branch 'master' of github.com:moztw/central
os detector: add ios
download btn os 判斷
Merge branch 'master' of github.com:moztw/central
Merge remote-tracking branch 'moztw/master' into inc-change
Adding Feature Block

Also adding CSS style for line in feature block.