Fix the unit tests.

[tewalds]

Fix the unit tests, by mocking stdout and closing the replay file properly. Make the unit test runnable. Also improve setup.py with the extra dependencies.

[eagleflo]

Looks good! I'd like to use the built-in https://docs.python.org/3/library/unittest.mock.html with Python 3, so mock would become a conditional dependency for Python 2.x.

Tiny nitpick: the commit title is a bit long. Fix the unit tests would be a better title, with the rest pushed into the commit message itself.

[tewalds]

Done.

[eagleflo]

Thank you!