Updated openstack/openstack
Project: openstack/horizon  322004f8480e40af5e77ed843ff803005d5af27c

adapt to python-novaclient-2.18.0

Novaclient renamed HTTPNotImplemented to HttpNotImplemented
and changed the attribute code to status in exceptions

This change should make the code work on newer and older versions.

Change-Id: Ifef6c4c1b2924b03df00f427cfe3e6a7f415e569
Closes-Bug: #1340596