Handling re-delete in rackspace db resource

Current implementation of db resource throws exception if the
resource was already deleted(All the other resources are not
throwing). This fix is to make db resource behavior similar to
other resources.

Fixes Bug #1197077

Change-Id: I4537180115400e6f6183e72a74bdd3ada220a3fa
Merge "Handling re-delete in rackspace db resource"