Make Heat's non_empty_stack usable without a server

We don't really need to test with a server to check Heat's
API responses. So just use a trivial resource type (a LaunchConfig)
to create some objects that we can query against. Now we can use
this test to gate.

Change-Id: I71bc065d8a1d2064ca90406543a376ce4d477275
Merge "Make Heat's non_empty_stack usable without a server"