Add a switch to allow a user to place their own public ssh key in authorized_users.

[sbates130272]

Nice project! Can we consider adding a feature that allows the user to specify a SSH key-pair different to the vagrant key?

[mgax]

Thanks! In principle I agree that only supporting the Vagrant key is not great, but a proper solution is tricky. For instance, it's possible to change the key right after the SSH port is up, but that still allows a window of opportunity to log in with the insecure key. So you kinda have to inject the private key beforehand, using e.g. cloud-init, which is not going to be supported by all images.