Till now, boxpy was based on the fact, that there was power_state
section, and there was a check if VM is down already. That approach have
their own issues.
Now, there will be no more power-off, there is a check by using
`cloud-init status` command through ssh.
Cleanup/destroy parts has needed some modification, so that there will
be no leftovers from cloud init ISO image.
And finally, there was some tweaks for user-data cloud-init part (mainly
for ssh handling), so that `cloud-init status` will not report phony
errors.
