Python 2.6 compatible string formatting
Python 2.6 compatible dict comprehensions
Fix inspect.getmembers for Python 2.6

Python 2.6 ships broken inspect.getmembers that always fails
for django-fsm.
Account for Python 2.6 in tox and travis
List Python 2.x supported versions in trove
Merge pull request #54 from opennode/python-2.6

Support for Python 2.6