Remove `allow_tags` usage
Remove `allow_tags` usage

Support for the `allow_tags` attribute on `ModelAdmin` methods was
removed in Django 2.0. Use `mark_safe` instead to get `language_column`
and `all_languages_column` to render properly in Django 2.0.

django-parler/django-parler,edoburu/django-parler,edoburu/django-parler,django-parler/django-parler