curl to wget in verify image service installation
curl to wget in verify image service installation

Changing "curl" to "wget" in "Verifying the Image Service installation"
 page. This is because Ubuntu doesn't include curl in the default
base/minimal installation.

Change-Id: I16364d05085a2a9c3713e94f71a3250215361540
Closes-Bug: #1248605
backport: havana

kairoaraujo/openstack-manuals,saeki-masaki/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,potsmaster/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,saeki-masaki/openstack-manuals,Akasurde/openstack-manuals,gongysh2004/openstack-manual,kairoaraujo/openstack-manuals,gongysh2004/openstack-manual,openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,potsmaster/openstack-manuals,Akasurde/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals