Fix Answer's class conflict

We have two models called `Answer`: The `Answer` model and the `Poll::Answer` model.

This conflict ocurrs when trying to create a user generated poll for a proposal. from the Dashboard. In that case we are getting an exception, only in the development environment, as the class `Answer` is loaded before the class `Poll::Answer` which is the one we want to use.

With this commit we are explicitly requiring the correct model, solving the class conflict.

app/models/poll.rb

@@ -1,4 +1,6 @@
 class Poll < ApplicationRecord
+  require_dependency "poll/answer"
+
   include Imageable
   acts_as_paranoid column: :hidden_at
   include ActsAsParanoidAliases