Fixing librarian-ansible so it works!!

In Ansible, `roles` are the community-shareable unit of configuration management code distributed through the [Ansible Galaxy Site](https://galaxy.ansible.com).  Although modules are indeed also developed by the community and shared via the [modules-extras project](http://github.com/ansible/ansible-modules-extras), the [Ansible Modules Documentation]() has a note saying that they're incorporated into Ansible core and packaged alongside Ansible:

>  Should you develop an interesting Ansible module, consider sending a pull request to the modules-extras project. There’s also a core repo for more established and widely used modules. “Extras” modules may be promoted to core periodically, but there’s no fundamental difference in the end - both ship with ansible, all in one package, regardless of how you acquire ansible.

Therefore, the use case for `librarian-ansible` or a bundler-like tool is more applicable to installing [Ansible Roles](http://docs.ansible.com/playbooks_roles.html#ansible-galaxy) from Galaxy.


*Changes:*

 - Move `resolve_with_librarian` to `#prepare_roles` function

 - Ensure roles in Ansiblefile are installed to sandbox roles path: `tmp_roles_dir`

 - Fix `roles_path` in `ansible.cfg` so it points to top-level roles dir in `kitchen_root` (e.g.: `/tmp/kitchen/roles`)