Update image downloads to use direct REST
Update image downloads to use direct REST

Change-Id: Ie936fa80a961a427f86f39e498cb631ffbbc73e4

openstack/python-openstacksdk,openstack/python-openstacksdk,openstack-infra/shade,stackforge/python-openstacksdk,openstack-infra/shade,dtroyer/python-openstacksdk,stackforge/python-openstacksdk,dtroyer/python-openstacksdk