Jekyll 2.1, Liquid 2.6, Redcarpet 3.1.
Bump jekyll-sitemap up to 0.5.0

https://github.com/jekyll/jekyll-sitemap/compare/v0.3.0...v0.5.0
Lock pygments.rb and rouge.
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