Add os-tenant-networks test

Nova API contains os-tenant-networks API which is one of Neutron
proxy API, but Tempest doesn't test the API now.
This patch adds a test for the API.

* The response of "list tenant-network" API
  {"networks": [
      {
          "cidr": "None",
          "id": "1b64ee34-161c-4889-b8c4-7ebb235647e3",
          "label": "private"
      },
      {
          "cidr": "None",
          "id": "b3aca3f0-2b4b-4687-9acc-66ad82397012",
          "label": "public"
      }
  ]}

* The response of "get tenant-network" API
  {"network": {
      "cidr": "None",
      "id": "1b64ee34-161c-4889-b8c4-7ebb235647e3",
      "label": "private"
  }}

Change-Id: I770b7438821e7924a315fe506838c48ef9bf1bd6
4 files changed