Recent changes to the test runner setup ended up causing Subversion unit

tests to fail to run. The __test__ = False on the common test class

was respected, but carried through to the subclasses, preventing any

PySVN or Subvertpy tests from running.
This sets __test__ = True on both subclasses, allowing them to run

again.

Ran the Subversion unit tests. Verified they could now be run.