Fixing an issue with outputting from Catalyst.

The ForceOutput option for vtkCPDataDescription wasn't getting
used properly so this fixes that bug. I also added a test to
verify that exactly what we want is getting outputted, no
more and no less.

Change-Id: Ice0db520ebfc9bbf9308532d8dec6551d324824b
Merge topic '14062_test_catalyst_outputs' into next

87fbd48 Fixing an issue with outputting from Catalyst.