Help user setup SSH keys

[Apreche]

We currently require the user to setup SSH keypair authentication on their instance by themselves prior to using this tool. It would be very nice if a user could start a new instance at their cloud provider and not have to do anything to that instance whatsoever prior to using this tool.

We would probably need the user to provide the root password to the instance. Then we could create a non-root user, generate an SSH keypair, and set all of that up prior to starting the usual procedure. It would feel pretty magical for a user to get a full application stack live without ever having to personally connect to their instance. This, of course, should be optional. Also, whatever keys are generated should be provided to the user in case they need them.

We may also be able to use this opportunity to configure the instance's SSH daemon according to best practices.