Add production Dockerfile to ease Janitor deployments.

[jankeromnes]

[ishitatsuyuki]

Don't forget to mount the credentials as bind mounts; this may be a bit hard since we have multiple data files in repo root.

[jankeromnes]

Don't forget to mount the credentials as bind mounts; this may be a bit hard since we have multiple data files in repo root.

Thanks! But since this is mostly to accommodate Cloud Ops deployments, I think we'll wait and see how they expect credentials to be handled (e.g. via a mounted volume, or environment variables, or some command or API call...)