Run host lookup first for configure_mirror.sh
Run host lookup first for configure_mirror.sh

A cosmetic change to reduce the debug output on DNS failures. First
check for valid DNS, then proceed with configuration.

Change-Id: I3370a155bf6b49088c398dc9d4d572b6210b84b2
Signed-off-by: Paul Belanger <e7139c8e6c4ea75cc1c287ce081b2dc0f3ab39ec@redhat.com>

Tesora/tesora-project-config,openstack-infra/project-config,Tesora/tesora-project-config,openstack-infra/project-config