Add external compose support in the docker role

- Use ansible.posix.synchronize for compose.yml
- Set fact for compose service restarts
- Introduce plain Docker dev host
- Optionally verify repos via GPG before sync
- Hide docker_repos_path in .folder
- Tweak .env for conciseness
- Add --diff to Ansible in Vagrantfile
- Clean output with loop_control
- Embed GPG in base role

roles/docker/templates/docker-compose-env.j2

@@ -1,7 +1,6 @@
 # {{ ansible_managed }}
-
 {% if item.env is defined %}
 {% for kvpair in item.env.items() %}
 {{ kvpair.0 }}={{ kvpair.1 }}
 {% endfor %}
-{% endif %}
+{% endif %}