Use HTTPS to pull from rubygems.org

This corrects the warning when running `bundle install`

    The source :rubygems is deprecated because HTTP 
    requests are insecure. Please change your source to 
    'https://rubygems.org' if possible, or 
    'http://rubygems.org' if not.
Merge pull request #11 from adamnbowen/patch-1

Use HTTPS to pull from rubygems.org