Remove before validation callback

This was breaking nested poll_questions_answers when submitting
more than one new answer at a time.

app/models/poll/question/answer.rb

@@ -17,8 +17,6 @@ class Poll::Question::Answer < ActiveRecord::Base
   validates :title, presence: true
   validates :given_order, presence: true, uniqueness: { scope: :question_id }
 
-  before_validation :set_order, on: :create
-
   def description
     self[:description].try :html_safe
   end
@@ -29,10 +27,6 @@ class Poll::Question::Answer < ActiveRecord::Base
     end
   end
 
-  def set_order
-    self.given_order = self.class.last_position(question_id) + 1
-  end
-
   def self.last_position(question_id)
     where(question_id: question_id).maximum('given_order') || 0
   end