Add libvirt support
Add libvirt support

Set up memory sizes with libvirt. I'm not familiar enough with Ruby to
know if there's a way of combining the :virtualbox and :libvirt
stanzas...

(The box images still need to be mutated manually.)

Change-Id: Ic2d2531f4e696127155cf1522899591f61c7fa6e
Signed-off-by: Stephen Kitt <c64219c0e25aff6572376b1dfbf7cf444494f5c6@redhat.com>

opendaylight/netvirt,opendaylight/netvirt,opendaylight/netvirt,opendaylight/netvirt,opendaylight/netvirt