Slight refactor to accomodate Nose's test discovery.

This should resolve #19 - the problem was in how the metaclass "magic" was intercepting class definition. Nose saw that the base class was being defined, but it wasn't there when it came time to do introspection.

We fixed it by defining `__test__ = False` on the base class, and setting it to `True` upon definition in the metaclass.

There were also some setup and teardown methods containing the word "test" that Nose was seeing; those were renamed.