Depend on 'github-pages' to run Jekyll

'github-pages' is a Gem that contains the Gem dependencies used to run
GitHub Pages. By using it to run Jekyll locally, you ensure your site
will build properly when deployed to GitHub Pages.

To run locally with Bundler:

    bundle install
    bundle exec jekyll serve --watch
Merge pull request #10 from ssorallen/gem-dependencies

Depend on 'github-pages' to run Jekyll