Restrict the listed courses for the current user.

def get_queryset(self, request):
        ''' Restrict the listed courses for the current user.'''
        qs = super(CourseAdmin, self).get_queryset(request)
        if request.user.is_superuser:
            return qs
        else:
            return qs.filter(Q(tutors__pk=request.user.pk) | Q(owner=request.user)).distinct()