Use UUID-based mounts for create and import

Use UUID-based mounts for create and import

With this change we mount our root and swap filesystems in /etc/fstab
based on their UUID rather than on their device name. This makes the
system resistent to device name changes, and makes sure the operating
system will find its devices whether they're seen as scsi, ide, virtio,
or some other new type/name.

This change makes the OS be able to boot under KVM, but also
xen+paravirt_ops and other possibly other hypervisors.

Reviewed-by: imsnah