title: Sinon Fake server not auto responding
body: <p>Hi I am testing a collection using fetch, when I call it there is no answer from the fake server only after calling server.response I get the desired result.</p>
  
  <p>Why is that ?</p>
  
  <p>My code</p>
  
  <pre><code>  beforeEach( function() {
      server = sinon.fakeServer.create();
      server.autoRespond = true;
      colhedoraList = new ColhedoraList();
    });
  
  .
  .
  .
      var spy       = sinon.spy(colhedoraList, 'parse');
  
      server.respondWith("GET", "getColhedoraInfo",
        [200, {"Content-Type": "application/json"},
        '[{"id":"1","talhaoAtual":1,"posicionamentos":[{"lat":-23.9317401,"lng":-50.2210379,"elevadorLigado":true,"horario":"2012-09-21T11:27:58Z"},{"lat":-23.931544,"lng":-50.2161884,"elevadorLigado":true,"horario":"2012-09-21T11:28:02Z"}]}]']);
  
      colhedoraList.fetch({add: true});
      server.respond();
      expect(spy).toHaveBeenCalled();
      expect(spygmaps).toHaveBeenCalledTwice();
      expect(colhedoraList.get(1).get('talhaoAtual')).toEqual(1);    &lt;&lt;&lt; ALL EXPECTS FAIL, If I don't call respond().
  </code></pre>