Fix CLI neutron client to use keystone session
Fix CLI neutron client to use keystone session

This was updated elsewhere in Liberty to use sessions.  CLI needs
updating, too.

Closes-bug: #1514992

Change-Id: I87ca120ac14a52739371d33d830dddb0a45782d1

openstack/akanda-rug,stackforge/akanda-rug,openstack/akanda-rug,stackforge/akanda-rug