title: JayData oData request with custom headers
body: <p>I need to send custom headers to my wcf oData Service but with the following function the headers dont get modified.</p>
  
  <pre><code>entities.onReady(function () {
  
      entities.prepareRequest = function(r) {
          r[0].headers['APIKey'] = 'ABC';
      };
  
      entities.DataServiceClient.toArray(function (cli) {
          cli.forEach(function (c) {
              console.log(c.Name)
          });
      });
  });
  </code></pre>
  
  <p>headers are not affected. any clue?</p>
  
  <p>thanks!</p>