Make setup.py test run tests, include tox.ini to test in multiple environments.
Python 3.3 compatibility.
Test SQLAlchemy by default, as it uses an in memory SQLite DB (as opposed to MongoDB, which requires an external server.
Add tox support for separately testing mongo support. Doesn't run by default in case people don't have a local running mongo server.
Merge branch 'master' of https://github.com/jtushman/state_machine

Conflicts:
	state_machine/models/__init__.py
	state_machine/orm/base.py