Remove rouge for now.

We will consider again later.
Use jekyll-sass-converter v1.1.0.

https://github.com/jekyll/jekyll-sass-converter/releases/tag/v1.1.0
Bump to Jekyll v2.2.0
Merge pull request #75 from github/jekyll-2-1

Upgrade to Jekyll 2.1
Merge branch 'master' into jemoji-0-3-0