Single code base for Python 2.x and Python 3.x.
Travis: drop 3.2, skip conversion.
Skip 2to3 when installing.
Add six as requirement.
six not needed for tox (already in setup).
Fix tests for Python 2.
Fix range for Python 2.
Update changelog.
Merge pull request #7 from mcmtroffaes/feature/py-universal

Support Python 2 and 3 without 2to3.