title: Rails: Get outer class name inside concern
body: <p>How can I get the class name of a model I am including a concern into?</p>
  
  <p>I am creating a concern for a scope as described in here <a href="https://stackoverflow.com/a/14483808/1715035">https://stackoverflow.com/a/14483808/1715035</a> but need the model name for polymorphic search.</p>
  
  <p><code>self.table_name</code> works fine and so does <code>self.table_name.singularize.titleize.gsub(/\s+/, "")</code> but maybe theres an easier way to get the class name.</p>