vm-creator: Correctly handle forced shutdowns
vm-creator: Correctly handle forced shutdowns

Don't do any post-installation checks on a machine if its forced to
shutdown. This is not only the right thing to do but it also solves the
issue of live VMs getting automatically deleted on forced shutdown.

https://bugzilla.gnome.org/show_bug.cgi?id=685846

vbenes/gnome-boxes,vbenes/gnome-boxes