MultiprocessWSGITest wait for workers to die bug

MultiprocessWSGITest.test_terminate_sigterm
fails because the wait for workers to die is unreliable.

Parent process can now wait on child or grand-child
processes to complete before moving on. This allows
for grand-child (aka worker) processes to take as much
time as they need to shutdown. NOTE: If the processes
still take too long, they will be killed by the test
framework throwing the "TIMEOUT" exception.

Fixed pep8 issue with python3

closes bug #1218133

Change-Id: I0d2e34463860a8fa59d6eef0ffbf63341a002e3d
Merge "MultiprocessWSGITest wait for workers to die bug"