Add backup playbook.
Created by: axilleas
First attempt. This should be replaced with systemd services/timers like: https://github.com/rumpelsepp/gitlab-pkgbuilds/blob/master/gitlab/gitlab-backup.service
Created by: axilleas
First attempt. This should be replaced with systemd services/timers like: https://github.com/rumpelsepp/gitlab-pkgbuilds/blob/master/gitlab/gitlab-backup.service