Fixed ArticleListView not using published()
Fixed ArticleListView not using published()

Also, I think `SlugMixin` is useless as it is meant for detail views.

To investigate: cannot use `super().get_queryset().published()` (it raises an exception, not sure why) so using `self.model.objects` for now.
Ircam-Web/mezzanine-organization,Ircam-Web/mezzanine-organization