Add show_deleted parameter to stack-list API

Need to fix test_stack_describe_all and test_stack_describe_all_empty in
heat.tests.test_engine_service.StackServiceTest.  They're failing when
run with other tests in suite, but passing when run individually.

Try this:

testr run --analyze-isolation heat.tests.test_engine_service.StackServiceTest

Change-Id: I7b63c57fb7de4bf5768e87cc9c37e032f9fc8ca1