Add support for API servers on IPv6 addresses (#48)

* Remove duplicate file for deletion

* Add support for IPv6 clusters

To correctly escape IPv6 addresses when ports are used, they must be
wrapped in square brackets [1]. This patch adds support for that,
using Ansible's ipwrap filter [2].

[1]: https://datatracker.ietf.org/doc/html/rfc4038#section-5.1
[2]: http://docs.ansible.com/ansible/latest/collections/ansible/utils/docsite/filters_ipaddr.html#wrapping-ipv6-addresses-in-brackets

* Do not abort other molecule jobs on failure

* Fix cache keys for Vagrant boxes

* Molecule: Derive overrides.yml location from scenario dir

# Conflicts:
#	molecule/default/molecule.yml
#	molecule/ipv6/molecule.yml

molecule/resources/verify/from_outside/tasks/test/deploy-example.yml

@@ -34,7 +34,7 @@
 
     - name: Assert that the nginx welcome page is available
       ansible.builtin.uri:
-        url: http://{{ ip }}:{{ port }}/
+        url: http://{{ ip | ansible.utils.ipwrap }}:{{ port }}/
         return_content: yes
       register: result
       failed_when: "'Welcome to nginx!' not in result.content"