Fix test that checks ID rather than equality

CPython does not guarantee that the id() of integers will be the same
and they should therefore be tested with standard equality.
Extract common nosetest params into setup.cfg

Arguments in setup.cfg will always be loaded as the default parameters
when running nosetest
Tell setuptools to use nose testsuite

This allows us to run the full test suite (unit and functional) by using
the python setup.py test command.