change assertEquals to assertEqual

According to http://docs.python.org/2/library/unittest.html
assertEquals is a deprecated alias of assertEqual.

https://review.openstack.org/#/c/56652/ updates to a new version of
hacking that enforces H602. Turning that on requires this change to land
first.

Re-do of https://review.openstack.org/#/c/53510 since that is abandoned.

Change-Id: Ie621edc8770e2015df5712f77d4cf9679b02bd0f