Non-supported Highlighter

[smizell]

I received this when merging to master.

The page build completed successfully, but returned the following warning:

Your site is using the 'rouge' highlighter, which is not currently supported on GitHub Pages. Highlighting on your site has been disabled. To re-enable, change your 'highlighter' value to 'pygments' in your '_config.yml'. Check out https://help.github.com/articles/page-build-failed-config-file-error#highlighting-errors for more information.