Adds tenant network support to the client

Modifies novaclient, changing the existing networks implementation to a
more appropriate os-admin-networks namespace, and supplements with a
tenant-base network extenion that lives under the os-networks namespace
as a Nova API extension. Also removes from the duplicately named network
test methods.

Implements: blueprint tenant-networks

Change-Id: I54c9f017b86fc413f1646c7bded8cebd94f6a287