Clarify error message is from nova
Clarify error message is from nova

We pass on a nova error message to the user when we have it - but
sometimes hat error message looks like:

  Build of instance 7bbfc561-5a4a-4fc7-8f5c-02e60bc61511 aborted: Request to https://network.example.com/v2.0/ports.json timed out

which can look like it was openstacksdk having issues talking to the
ports api, when it was really nova.

Add a few words to clarify.

Change-Id: Ibd95c8d57f3e070760d0f98b2642e3cbf552c5b8

dtroyer/python-openstacksdk,openstack/python-openstacksdk,dtroyer/python-openstacksdk,openstack/python-openstacksdk,stackforge/python-openstacksdk,stackforge/python-openstacksdk