mkcloud: make volume group name variable
mkcloud: make cloud name variable
mkcloud: dont setup nova_fixed network on host

this should be a cloud-internal network
mkcloud: drop explicit uuid

this is then randomly auto-assigned by libvirt
otherwise we would need to generate UUIDs for multiple clouds
mkcloud: allow virtual clouds with variable admin net
mkcloud: better cleanup network
mkcloud: use per-instance mountpoint
mkcloud: enable ksm on host

this can save multiple GB RAM
especially when running multiple clouds in parallel