Log HttpError in destroy before converting
Log HttpError in destroy before converting

We're converting a pypowervm HttpError to a nova
InstanceTerminationFailure in the destroy flow, and losing the
HttpError's traceback as a result.  This change set adds a log of the
original exception to improve FFDC.

Change-Id: Ia0ba8226e2c128bc3433b7f179acb552469d997d

stackforge/nova-powervm,stackforge/nova-powervm,openstack/nova-powervm,openstack/nova-powervm