Directory index rendering fails for non-admins.

Sentry Issue: ACE4-26

AttributeError: 'map' object has no attribute 'filter'
  File "ace4/cms/views.py", line 201, in dispatch
    return render_fileobject(request, path, obj, recurse, size_spec)
  File "ace4/cms/views.py", line 558, in render_fileobject
    content = dir_styles[style](request, path, obj)
  File "ace4/cms/views.py", line 366, in render_directory_index
    entries = entries.filter(status=S_PUBLISHED)

The problem here is that the .filter(status=S_PUBLISHED) is applied to something that isn't a queryset anymore. We have to move the check a few lines up so we can still do it on a queryset.