Upgrade to Ruby 2.1.1

This upgrades Ruby to version 2.1.1.

I also had to switch `jazz_hands` to a version where you specify your own debugger since `pry-debugger` is not compatible with ruby 2.1.

After upgrading Ruby, I tried unsuccessfully to upgrade Rails to 4.0.4. Version 4.0.4 is supposed to fix an issue with the Postgres adapter: https://github.com/rails/rails/issues/12867.

However, after upgrading, I kept getting a wrong number of arguments (2 for 1) error for line 12 of `app/views/layouts/_head.html.erb` which is calls the `stylesheet_link_tag` method. After much googling and trying out all sorts of different things, I wasn't able to figure it out.

Quick tip for anyone that tries upgrading to Rails 4.0.4, make sure to upgrade `protected_attributes` as well. If you don't, all of the specs that use FactoryGirl will fail. It took me a while to figure that out.