Add verbosity levels

I've cleaned up and fixed the RSpec tests into the `spec` directory.  To run them simply run `rspec` as normal from top-level dir of this gem repo.  I have also added spec tests for this new feature:  `ansible_verbosity`!

The verbosity setting can be set in a `.kitchen.yml` like this:

    ---
    driver:
        name: vagrant
    
    provisioner:
      name: ansible_playbook
      roles_path: roles
      hosts: foobar
      require_ansible_repo: true
      ansible_verbose: true
      ansible_verbosity: 2

This will set the verbosity flag appropriately (e.g.: `1 => '-v', 2 => '-vv', 3 => '-vvv" ...`) Valid values are one of: `1, 2, 3, 4` OR `:info, :warn, :debug, :trace`.