Add questions with mutiple answers to polls public interface

The `reload` method added to max_votes validation is needed because the
author gets here with some changes because of the around_action
`switch_locale`, which adds some changes to the current user record and
therefore, the lock method raises an exception when trying to lock it
requiring us to save or discard those record changes.

config/locales/es/general.yml

@@ -636,6 +636,9 @@ es:
     show:
       vote_answer: "Votar %{answer}"
       voted: "Has votado %{answer}"
+    description:
+      unique: "Puedes seleccionar un máximo de 1 respuesta."
+      multiple: "Puedes seleccionar un máximo de %{maximum} respuestas."
   proposal_notifications:
     new:
       title: "Enviar notificación"