integration tests do not assert that cleanup delete succeeds

[Steve Baker]

Currently integration and functional tests delete stacks on cleanup, but do not wait for delete success before finishing the test.

This leads to tests passing when the stack is left behind in a DELETE_FAILED state.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/214410

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/214410
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=3dbfb0fd92f35949dae1d0f703ffcc2e2d09b7bb
Submitter: Jenkins
Branch: master

commit 3dbfb0fd92f35949dae1d0f703ffcc2e2d09b7bb
Author: Steve Baker <email address hidden>
Date: Wed Aug 19 13:37:08 2015 +1200

    Assert DELETE_COMPLETE on all stack delete cleanup

    Currently stacks are deleted on integration test cleanup but no
    polling is done for DELETE_COMPLETE, so the test will pass even though
    the stack may be in a DELETE_FAILED state.

    This change uses _stack_delete for all cleanup stack deleting, which
    polls for complete.

    Change-Id: Ic44b27130596cf3fa8616608a091b683ea131e0b
    Closes-Bug: #1486303