translations: Show translated language name

On a preview we came up with "Page not available in Deutsch", which is
obivously wrong. Translate the language name as well, so that it fits to
the rest of the phrase.

mpicms/base/mixins.py

@@ -78,7 +78,7 @@ def preview_text(self):
     def serve(self, request):
         lang = request.LANGUAGE_CODE
         if not getattr(self, 'body_' + lang) and self.body:
-            messages.info(request, _('Page not available in %s') % get_language_info(lang)['name_local'])
+            messages.info(request, _('Page not available in %s') % get_language_info(lang)['name_translated'])
 
         return super().serve(request)