title: ActiveAdmine register_page and controller
body: <p>What will be the link to an action defined like this:</p>
  
  <pre><code>ActiveAdmin.register_page "such_page" do
  
  
    content title: 'A page' do
      columns do
        column do
          render partial: 'index'
        end
      end
    end # content
  
    action_item do
      link_to('Perform', 'such_page/much_action')
    end
  
  controller do
      def much_action
        puts 'Wow, actually doing!'
        redirect_to 'http://stackoverflow.com'
      end
  end
  </code></pre>
  
  <p>I supposed that link will be just like mentioned in <code>action_item</code>, but is leads to 404 error page. Did I forgot to add some routes or am I wrong about how ActiveAdmin <code>register_page</code> and controller cooperate?</p>