Rackspace Cloud Database resource catches incorrect exception on delete

[Randall Burt]

During handle_delete, this resource checks for a NotFound exception in order to detect if the physical resource has already been deleted. However, the client library throws a generic ClientException for this case. This bug results in un-deletable stacks since handle_delete will always fail with a ClientException.

Reproduce:

1. Create a stack with a Rackspace::Cloud::DatabaseInstance resource
2. Via the Trove or Rackspace DBaaS api, manually delete the instance
3. Call stack-delete on the stack.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/50390

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/50390
Committed: http://github.com/openstack/heat/commit/74b5d7b60d42bd8e10a41bb4c74d80c85293160b
Submitter: Jenkins
Branch: master

commit 74b5d7b60d42bd8e10a41bb4c74d80c85293160b
Author: Randall Burt <email address hidden>
Date: Mon Sep 30 20:43:02 2013 -0500

    Catch the appropriate exception for missing instance

    Catch ClientException instead of NotFound since this is
    what the underlying client library actually throws.

    Closes-Bug: #1236911
    Change-Id: I1e7f3c69c216d19705cab9bdcd7302e1b917fdd4