Use session for neutron client
Use session for neutron client

python-openstack client is now using sessions to create clients. This
patch implements creating Network client using sessions.

Related to c3c6edbe8a083aef0fb6aea3cb461ff8e715fc59

Change-Id: If90ac705eb11dfc1e3abbe2ce18c3d8ccefdbdfb
Closes-Bug: 1411179

dtroyer/python-openstackclient,BjoernT/python-openstackclient,openstack/python-openstackclient,redhat-openstack/python-openstackclient,BjoernT/python-openstackclient,redhat-openstack/python-openstackclient,dtroyer/python-openstackclient,openstack/python-openstackclient