Add exceptions messages for authentication
Add exceptions messages for authentication

Fixes bug 1125137

Change-Id: Id79d11fb515a7af3b4e5cbe87bc717880fdb268b

citrix-openstack-build/python-neutronclient,ntt-sic/python-neutronclient,cernops/python-neutronclient,noironetworks/python-neutronclient,CiscoSystems/python-quantumclient,cryptickp/python-neutronclient,asadoughi/python-neutronclient,venusource/python-neutronclient,CiscoSystems/python-neutronclient,sajuptpm/python-neutronclient-ipam,Juniper/python-neutronclient,vijayendrabvs/ssl-python-neutronclient,ntt-sic/python-neutronclient,Juniper/python-neutronclient,JioCloud/python-neutronclient,venusource/python-neutronclient,huntxu/python-neutronclient,varunarya10/python-neutronclient,yamahata/python-tackerclient,cryptickp/python-neutronclient,yamahata/python-tackerclient,noironetworks/python-neutronclient,CiscoSystems/python-quantumclient,johnpbatty/python-neutronclient,Stavitsky/python-neutronclient,sajuptpm/python-neutronclient-ipam,roaet/python-neutronclient,cernops/python-neutronclient,citrix-openstack-build/python-neutronclient,CiscoSystems/python-neutronclient,NeCTAR-RC/python-neutronclient,rackerlabs/rackspace-python-neutronclient,vichoward/python-neutronclient,rackerlabs/rackspace-python-neutronclient,asadoughi/python-neutronclient,eayunstack/python-neutronclient,varunarya10/python-neutronclient,mangelajo/python-neutronclient,openstack/python-neutronclient,NeCTAR-RC/python-neutronclient,openstack/python-neutronclient,mangelajo/python-neutronclient,johnpbatty/python-neutronclient,Stavitsky/python-neutronclient,roaet/python-neutronclient,eayunstack/python-neutronclient,JioCloud/python-neutronclient,vichoward/python-neutronclient,vijayendrabvs/ssl-python-neutronclient,huntxu/python-neutronclient