Added python 3 support
Added python 3 classifiers
Fixed flake8 E128 error in tests.py
Added python 3 and django 1.5 to travis config
Merge branch 'feature/py3-support' of git://github.com/rafales/django-appconf into rafales-feature/py3-support

Conflicts:
	appconf/tests/tests.py
Updated versions in the tox config.