tests: provide a way use libvirt with vagrant and tox
tests: provide a way use libvirt with vagrant and tox

This allows for:

tox -- --provider=libvirt

Signed-off-by: Andrew Schoen <aschoen@redhat.com>

Resolves: vagrant#boxes

font/ceph-ansible,jsaintrocc/ceph-ansible,jtaleric/ceph-ansible,albertomurillo/ceph-ansible,albertomurillo/ceph-ansible,guits/ceph-ansible,bengland2/ceph-ansible,ceph/ceph-ansible,travmi/ceph-ansible,font/ceph-ansible,WingkaiHo/ceph-ansible,ceph/ceph-ansible,bengland2/ceph-ansible,WingkaiHo/ceph-ansible,fgal/ceph-ansible,guits/ceph-ansible,travmi/ceph-ansible,albertomurillo/ceph-ansible,jsaintrocc/ceph-ansible,jtaleric/ceph-ansible,fgal/ceph-ansible,WingkaiHo/ceph-ansible