RCv3 positive integration tests

This appears to only be used for logging. The `logging` module knows how to get all of this interesting stuff for you in the log messages, including line number (`%(lineno)d`); see [the documentation](https://docs.python.org/2/library/logging.html#logrecord-attributes) for more details.

I don't know if we ever intend this to run on `PyPy` (it's sufficiently far away from a unit test suite and sufficiently close to more realistic code it may be worth a shot), but it's worth noting that on most Python implementations, this comes with a pretty big performance cost. One good reason to use the logger is that it's very easy to enable it *just* for instrumented test runs, if that cost becomes prohibitive.