Drive the DNS installation completely with Ansible (#311)

* Remove RHN and dependencies from Heat templates

The templates will just deploy the OpenStack resources from now on. Any
configuration or dependency installation will be handled by Ansible.

* Add outputs to the Heat templates

These outputs will be consumed by Ansible so we'll no longer need the
Python scripts and templates to generate the inventory.

* Add `become: true` to the bind-server playbook

The playbook requires root privileges and this was achieved in
bin/full-service.sh by passing `--become` to `ansible-playbook`.

Since we'll be invoking the playbook directly, we just ask for sudo
where necessary instead.

* Add the "all in one" ansible playbook

* Update the readme

* Remove the old files

The move to a full ansible installation means most of the files under
`bin` and the heat environment files are no longer needed.

* Fix yamllint errors