Update Travis w/Ruby 2.1.0, new Rubinius, Rails 4.1.0.beta1

1. Added Ruby 2.1.0 to the .travis.yml
2. Updated the Rubinius label and included required Rubinius gems
3. Added a gemfile for ActiveRecord 4.1.0.beta1
4. Minor changes to allow specs to run across different Ruby/ActiveRecord combinations.