导航增加 Gems

Merge pull request ruby-china#555 from ruby-china/upgrade/rails-5

Upgrade Rails 5

Merge pull request ruby-china#539 from ruby-china/use-activerecord

Use ActiveRecord

Move sanitize to last call

降低搜索结果匹配度，以让 Ruby 这样一个词的能出来;

WillPaginate default inner_window = 2

.

字体修正;

Merge pull request ruby-china#246 from loveky/master

Fix Typo in README.md

Exclude current topic from recent topics list of the node

Fixed ruby-china#180