Add tox.ini for tox (http://tox.testrun.org/)
tox.ini: Use {posargs} so one can specify tests to run
tox.ini: Add ipdb as dep, because it's useful for debugging
tox.ini: Add support for testing with Python 2.5
Merge pull request #38 from msabramo/tox

Add tox.ini for tox (http://tox.testrun.org/)