title: Get /collection/id in backbone without loading the entire collection
body: <p>Is there a way to load a single entity of a Backbone collection (from the server)?</p>
  
  <pre><code>Backbone.Collection.extend({
    url: '/rest/product'
  });
  </code></pre>
  
  <p>The following code can load the entire collection with a <code>collection.fetch()</code> but how to load a single model? <a href="http://documentcloud.github.com/backbone/#Sync" rel="noreferrer">Backbone's documentation</a> says clearly that <code>GET</code> can be done <code>/collection[/id]</code> but not how.</p>