Use config region_name_for_services for rackspace clients
Use config region_name_for_services for rackspace clients

This deletes the region_name configuration option and replaces
uses with region_name_for_services.

There is no need for a different configuration option
for rackspace clients.

Change-Id: I6866026a0b9a1895b9b062e9c49e0fe54ec8e831

miguelgrinberg/heat,rdo-management/heat,srznew/heat,miguelgrinberg/heat,jasondunsmore/heat,dims/heat,takeshineshiro/heat,pshchelo/heat,rdo-management/heat,takeshineshiro/heat,pshchelo/heat,maestro-hybrid-cloud/heat,noironetworks/heat,pratikmallya/heat,steveb/heat,cwolferh/heat-scratch,dragorosson/heat,rh-s/heat,openstack/heat,redhat-openstack/heat,noironetworks/heat,pratikmallya/heat,cryptickp/heat,gonzolino/heat,srznew/heat,dragorosson/heat,openstack/heat,maestro-hybrid-cloud/heat,cwolferh/heat-scratch,redhat-openstack/heat,jasondunsmore/heat,cryptickp/heat,rh-s/heat,steveb/heat,dims/heat,gonzolino/heat