Py3 changes, Py2 backwards compatibility fix

Rationale: Target current Python release and provide *backwards* compatibility if needed. Don't target legacy releases.
Tested (in app) with Python 3.4 and loaded with Python 2.7.
Updated setuptools classifiers

I have no tox at hand so my integration "tests" should be validated properly for all Python releases (2.7, 3.2, 3.3, 3.4?). `2to3` only really complained the import of Queue so I changed only that but you may want to validate all other issues as well.
Merge remote-tracking branch 'origin/py3py2'