Add Traefik to Swarmstack? #14

Hi @mh720 ,

I've added Traefik to our Swarmstack implementation with Grafana dashboard as well. I can submit a PR with the changes if you'd like.

Changes include:

• service definition in docker-compose.yml
  • traefikcerts docker volume.
  • traefik_config configuration with traefik.toml in it.
  • grafana_dashboard_traefik-dash grafana dashboard.
• TRAEFIKDOMAIN in ansible/clusters/swarmstack inventory
• steps in ansible/playbooks/swarmstack.yml to customize traefik.

Please, let me know your thoughts.