Add more unit tests for the engine API
Add more unit tests for the engine API

Verify the following endpoints:
 - list_stack_resources
 - describe_stack_resources
 - describe_stack_resource

Additionally, check for presence of the correct output keys from the
following endpoints:
 - list_stacks
 - show_stack

Note that some tests are commented out because they are currently failing.
This will be fixed in a future patch.

Change-Id: I1c8c46283c1217789e3d4dea7aeac11c991bcef4
Signed-off-by: Zane Bitter <1899fff8e7db19a598ee9d835aa1a232f82ea264@redhat.com>

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