heat tests : Improve resource.py test coverage
heat tests : Improve resource.py test coverage

Add tests for good/error paths of create/update functions

ref bug 1146529

Change-Id: I2b50b94e61a85a681575fbe6cad5576f2df311b9

srznew/heat,pshchelo/heat,jasondunsmore/heat,JioCloud/heat,dragorosson/heat,rickerc/heat_audit,noironetworks/heat,steveb/heat,citrix-openstack-build/heat,pratikmallya/heat,pratikmallya/heat,cryptickp/heat,gonzolino/heat,jasondunsmore/heat,Triv90/Heat,openstack/heat,varunarya10/heat,Triv90/Heat,rdo-management/heat,cryptickp/heat,dims/heat,citrix-openstack-build/heat,takeshineshiro/heat,srznew/heat,maestro-hybrid-cloud/heat,JioCloud/heat,cwolferh/heat-scratch,rh-s/heat,pshchelo/heat,rdo-management/heat,varunarya10/heat,rickerc/heat_audit,miguelgrinberg/heat,Triv90/Heat,ntt-sic/heat,openstack/heat,redhat-openstack/heat,NeCTAR-RC/heat,takeshineshiro/heat,ntt-sic/heat,noironetworks/heat,maestro-hybrid-cloud/heat,dragorosson/heat,cwolferh/heat-scratch,NeCTAR-RC/heat,dims/heat,redhat-openstack/heat,gonzolino/heat,rh-s/heat,miguelgrinberg/heat,steveb/heat