Add a commons-net bundle

net-virt depends on commons-net, so bundle it explicitly in the
relevant features instead of relying on neutron to provide it for
us. (This avoids errors when ovsdb builds with a newer version than
neutron.)

Change-Id: Ifd4b7909b44a824f7ebb0347753502c9e509c96e
Signed-off-by: Stephen Kitt <skitt@redhat.com>