after a tenant has deleted a resource, subsequent calls on new resources are dropped

[Adam Gandelman]

The tenant resource cache, which we use to cache the id of tenant resources so as to avoid neutron calls, never removes its entries when a resource is deleted. This causes an issue where a tenant cannot re-create a deleted resource, ie:

* Create a network, subnet, router, etc.
* Delete router interface, delete subnet, delete router, delete network
* Create a network, subnet, router
* The orchestrator gets the create event, attempts to resolve the router id via the cache, gets the previous router and ignores message because it is a message for a deleted resource.

We need to add some callbacks to invalidate entries from the resource cache when we do the rest of deletion.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/264340

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/264340
Committed: https://git.openstack.org/cgit/openstack/astara/commit/?id=5fed2a704162d4277e6ab5e4e187c01ced440aeb
Submitter: Jenkins
Branch: master

commit 5fed2a704162d4277e6ab5e4e187c01ced440aeb
Author: Adam Gandelman <email address hidden>
Date: Wed Jan 6 12:24:50 2016 -0800

    Cleanup deleted resource from the tenant resource cache

    When a resource is deleted, its not currently removed from the tenant
    resource cache. This causes a cache hit if the tenant attempts to re-create
    the same type of resource, but the resource is then later ignored because
    it has been deleted. This adds a callback used by the TRM to remove it
    from the resource cache when its state machine is deleted.

    Change-Id: I5dcbeda7de240a693fc7a4944dd34a37b10d174b
    Closes-bug: #1531597