Added a new associate method, to associate a row in the cart with a model, so you can access the model from the CartRowCollection

tests/helpers/NamespacedProductModelStub.php

@@ -0,0 +1,5 @@
+<?php namespace Acme\Test\Models;
+class TestProduct {
+	public $description = 'This is the description of the namespaced test model';
+	public function find($id) { return $this; }
+}