去掉新手10回复发帖限制
优化 /notifications;
Merge branch 'master' of github.com:ruby-china/ruby-china
个人主页首页的帖子按照受欢迎度排序;
会员栏目改为 Top 100 活跃会员，去掉新注册会员的罗列；
个人主页受欢迎的帖子列表排除掉某些节点.
Reproduce #173 using rspec.
Replace user placeholder in code after markdown.
Merge pull request #174 from doitian/bug/173-user-placeholder-in-coffee

Bug/173 user placeholder in coffee
Add rpm.
回帖快捷键支持 Command + Enter; #176
gravatar_proxy 改回默认的 gravatar 官方地址
Exclude current topic from recent topics list of the node

Fixed #180
Update to Rails 4.
Fix test cases.
Fix assets complie.
Fix scaffold template for Rails 4.
Fix assets precomplie bug.
修正缺少的图片文件;
修正通知没有 updated_at 属性，导致 cache digest 计算错误的问题;