Some more cosemtic changes

GitHub.com the website would like to use html-proofer for link UI and mailers. There's a dependency problem though:

```
Bundler could not find compatible versions for gem "nokogiri":
  In Gemfile:
    html-proofer depends on
      nokogiri (~> 1.6.0)

    gollum depends on
      nokogiri (1.5.11)
```

Let's fix that.