title: ActiveModel Serializer: access attributes as methods
body: <p>How can I access the defined attributes in a serializer as a methods?</p>
  
  <pre><code>class Test &lt; ActiveModel::Serializer 
    attributes :a, :b, :c
  end
  
  s = Test.new(Object)
  s.a
  </code></pre>
  
  <p>I need this for delegation, it used to be available in version 0.8/</p>