Refs #13 - Introduces common django config then overrides it for all exi...

...sting django versions available today. No magic for now, new configs classes will be needed when releases will come.
I see you handled "New in Django 1.6." settings.
Did you reviewed "Changed in Django 1.6" ones? See https://docs.djangoproject.com/en/1.6/releases/1.6/

If the change is about default value and this default value is inherited from Django's global_settings, that's ok.