Switch to Kramdown

[ryanfb]

From GitHub:

The page build completed successfully, but returned the following warning for the gh-pages branch:

You are currently using the 'rdiscount' Markdown engine, which is no longer supported by GitHub Pages and may cease working at any time. To ensure your site continues to build, remove the 'markdown' setting in your site's '_config.yml' file and confirm your site renders as expected. For more information, see https://help.github.com/articles/updating-your-markdown-processor-to-kramdown/.

For information on troubleshooting Jekyll see:

https://help.github.com/articles/troubleshooting-jekyll-builds