Add unittest for #62

Not sure it's worth it, but now it's done ;)
I've added a hard coded `JAVA_BIN=java` through `override_settings`, which is not that elegant, but I've had no better idea (unless mocking).
Also, to make the tests runs, I've tweaked a little bit the settings (but not pushed) for django 1.6: `STATIC_URL` missing a final /, added a missing `SECRET_KEY`, this kind of things. Not sure how you run your tests though ;)

Thanks :)

Yohan