title: ruby active model serializer association on version > 0.8.0
body: <p>How do I get this relation to work with the new version?</p>
  
  <pre><code>class UserSerializer &lt; ActiveModel::Serializer
    embed :ids
    attributes :id, :email, :created_at, :updated_at, :auth_token
  
    has_many :products
  end
  </code></pre>
  
  <p>works with </p>
  
  <pre><code>gem "active_model_serializers", "~&gt; 0.8.0"
  </code></pre>
  
  <p>but, doesn't work with </p>
  
  <pre><code>gem 'active_model_serializers', git: "https://github.com/rails-api/active_model_serializers.git"
  </code></pre>