This migrates the above files from tempest. This includes tempest commits:
* networks_client.py: I953c9daf10e8b0d07f6999fd4a61330222c1d2e5
* test_networks_client.py: I3ad6761651cec5e66012d08e6b63322f53286a5c
to see the commit history for these files refer to the above Change-Ids in the tempest repository
Partially implements blueprint migrate-service-clients-to-tempest-lib
Change-Id: I3d14142e78f72876e4cdc6ce3d3c7cd210b3c670