manual provisioner should carry out configuration for ssh-keys-per-user, machine-updates-authkeys

[Andrew Wilkins]

From a review comment on manual provisioner:

"If/when ssh-keys-per-user, and machine-updates-authkeys, functionality
lands, this'll make manually provisioned machines second-class citizens. I think
we should aim to minimize the observable differences between manually and
automatically provisioned machines, really."

[Andrew Wilkins (axwalk)]

I think there might be cause for making this optional. I imagine some people might want to provision agents on the target machine, but not necessarily modify their SSH configuration (for security reasons).

[Andrew Wilkins (axwalk)]

We should just use cloud-init, or at least some new command using the cloud-init Python package. This would make manual provisioning more like everything else. See comments on lp:1238934.