This migrates the above files from tempest. This includes tempest commits:
* tenant_usages_client.py : I0e6287b1a720d5f3f129fcaa8c08cf6d40abf8e8
* tenant_usages.py : If07f0a929c7085090bcefd4d2d565b896bf438f3
* test_tenant_usages_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: I94fc27bdb30e69ac22b5418d6dca0a06f51874c6