Replace assertEqual(None, *) with assertIsNone(*)
Replace assertEqual(None, *) with assertIsNone(*)

This patch is going to replace assertEqual(None, *) with
assertIsNone(*) in unit test code to have more clear messages
in case of failure.

Change-Id: I6f85498347e8fc7cad5ea7afb832b9acda7daafc

dtroyer/osc-lib