virt_util: host may be a dict()
virt_util: host may be a dict()

Where there is only one host IP in a DHCP lease record, we get a dict with
the host details. The code base except instead a list of host.
This patch convertes the host value in this case.

Change-Id: I97aa6968f6db08bfb3e5d2f32ad08aa02d8b15fd

redhat-openstack/infrared,redhat-openstack/infrared,redhat-openstack/infrared