Improve feedback if vice-setup fails to create root volume

[krichter722]

If vice-setup fails to create a root volume (before printing Now I'll try to create an initial root volume and following output), there's no feedback for the user except return code 1. Without checking the returncode the user might easily assume that vice-setup returned successfully. A message indicating the failure and explaining the reason (by forwarding a helpful error message or wrapping an unhelpful error message) would be very helpful.

experienced with 6.9.7-2+ubuntu16.04 on Ubuntu 16.04