This migrates the above files from tempest.
This includes tempest commits:
* snapshots_client.py : If7be1e24451b24fce03dcfc1394abb6260da460c
* test_snapshots_client.py : Idc31ee38fd9d5fd4873de6ba29550bdd5ce35043
* snapshots.py : I9694e36a7d0a8e9bd6cd66c9dc46a4a715d2c25f
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: I7854f7e080de9e819a1fae0d2de5d3aee111505a