base: use dig instead of nslookup
base: use dig instead of nslookup

nslookup cli does not work correctly when running serverspec. With dig,
all seems allright.

Signed-off-by: Emilien Macchi <d605a501dec15c980af71d9dfebf4b595ab6da1f@enovance.com>

redhat-cip/openstack-serverspec,enovance/openstack-serverspec