Add qemu-img also in nova-libvirt image
Add qemu-img also in nova-libvirt image

This is noop on CentOS (it was installed as a dep already - better
be explicit) but installs qemu-img (and other qemu utils) on
Debian and Ubuntu.

qemu-img may be used by libvirtd to create non-raw images as it
happens, e.g., when Kolla's libvirtd is used by tenks.

Change-Id: Ib79b8486f4d5064e4f249201d28cf5d6541c69ef

openstack/kolla,openstack/kolla