Update our mod_wsgi tests to catch regressions of issues like PYTHON-695.

A PyMongo application should run in mod_wsgi in a sub interpreter, with C extensions compiled. It should encode and decode pure-Python types: Binary (in Python 2), Code, ObjectId, DBRef, Timestamp, MinKey, MaxKey, Regex, and UUID. It should also encode and decode datetimes so it's required to import the "utc" timezone (in PyMongo 3, tz_aware is always on).

mod_wsgi_test.conf is currently configured as we recommend, to run PyMongo in the main interpreter. Make a copy that is misconfigured to use sub interpreters, see my blog post.