title: AngularJS $resource not sending custom headers
body: <p>I'm using angular and angular-resource version 1.1.5 and I'm using a $resource to make a request to a REST service. But it seems like the custom headers is not appended to the request. My definition is as below. Is there anything I did wrong?</p>
  
  <pre><code>myApp.factory('User', function($resource) {
      var User = $resource('http://localhost\\:7017/mydomain/users/jack', { }, {
          get: {
              method: 'GET',
              isArray: false,
              headers: {'X-Requested-By':'abc'}
          }
      });
      return User;
  });
  </code></pre>