- replace most explicitly-named test objects called "Mock..." with
actual mock objects from the mock library.  I'd like to use mock
for new tests so we might as well use it in obvious places.
- use unittest.mock in py3.3
- changelog
- add a note to README.unittests
- add tests_require in setup.py
- have tests import from sqlalchemy.testing.mock
- apply usage of mock to one of the event tests.  we can be using
this approach all over the place.
Added new flag ``retaining=False`` to the kinterbasdb and fdb dialects.
This controls the value of the ``retaining`` flag sent to the
``commit()`` and ``rollback()`` methods of the DBAPI connection.
Defaults to False.  Also in 0.8.2, where it defaults to True.
[ticket:2763]