Convert kickstart userdata to cloud-config, and take ssh-keys as params

Will require https://github.com/theforeman/foreman/pull/1586
> Using an unprivileged user by default is a good practice and I don't think we should muck with the default behaviors of cloud-init.  I'm not opposed to an option to do it I guess, although I'd rather users modify or create their own user data template if they want to do something like that.

You're right, we should match the "standard". I find it weird, this is
security by obstruction (users are known and have sudo access).

Anyway, this is good. I haven't tested this. Domain is correctly set.

:+1:

-- 
Later,
 Lukas #lzap Zapletal