add auth, so mgmt can be used on publicly accessible networks

[skyfaller]

Hi folks, is the FAQ up to date? It says "Auth hasn't been implemented yet, so you should only use it in trusted environments (not on publicly accessible networks) for now." https://github.com/purpleidea/mgmt/blob/master/docs/faq.md#is-this-project-ready-for-production

If that is still true, I can't use mgmt yet for my use cases, so I wanted to file an issue I could follow so I can see when it's worth trying mgmt.

If that is no longer true, could you please update the documentation? Thank you :)