Add human readable label

app/models/request_for_comment.rb

@@ -25,6 +25,10 @@ class RequestForComment < ActiveRecord::Base
             limit 1").first
   end
 
+  def to_s
+    "RFC-" + self.id.to_s
+  end
+
     private
     def self.row_number_user_sql
       select("id, user_id, exercise_id, file_id, requested_at, created_at, updated_at, user_type, row_number() OVER (PARTITION BY user_id ORDER BY created_at DESC) as row_number").to_sql