This migrates the above files from tempest. This includes tempest commits:
* migrations_client.py : Ice3665e91ff34409f6f105303213303d1fca1816
* migrations.py : I5e81dadd5dee4ecd85f309c34dae0d3ba0733a0d
* test_migrations_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: I0dbae04c479b9d742a3e51d1d60c372093c2c027