Delete python bytecode before every test run.
Delete python bytecode before every test run.

This should eliminate the need to clean -x -i to kill pyc files in
your local directory to get tests to pass.

Change-Id: Icb958a994f0864f11b4f4d091826f3530875fe44
Closes-Bug: #1368661

StackStorm/python-mistralclient,openstack/python-mistralclient,StackStorm/python-mistralclient,openstack/python-mistralclient