push commenters to RFC model

app/controllers/request_for_comments_controller.rb

@@ -68,11 +68,8 @@ class RequestForCommentsController < ApplicationController
   def set_thank_you_note
     authorize!
     @request_for_comment.thank_you_note = params[:note]
-    commenters = []
-    @request_for_comment.comments.distinct.to_a.each {|comment|
-      commenters.append comment.user
-    }
-    commenters = commenters.uniq {|user| user.id}
+
+    commenters = @request_for_comment.commenters
     commenters.each {|commenter| UserMailer.send_thank_you_note(@request_for_comment, commenter).deliver_now}
 
     respond_to do |format|

app/models/request_for_comment.rb

@@ -38,6 +38,14 @@ class RequestForComment < ActiveRecord::Base
     submission.files.map { |file| file.comments.size}.sum
   end
 
+  def commenters
+    commenters = []
+    comments.distinct.to_a.each {|comment|
+      commenters.append comment.user
+    }
+    commenters.uniq {|user| user.id}
+  end
+
   def to_s
     "RFC-" + self.id.to_s
   end