title: cg-busy on consecutive promises
body: <p>I have a factory which stores and periodically updates some data using a service($http call). I want the busy indicator in the view every time the data is being updated. The factory exposes the data object and the promise. </p>
  
  <pre><code>angular.module('myUI')
    .factory('statusFactory', function ($timeout, statusService) {
      var promise = {};
      var data = {};
  
      function update(){
          angular.extend(promise, statusService.status().$promise).then(function(response){
              angular.extend(data, response);
          });
          $timeout(update, 10000);
      }
      update();
  
      return{
          data: data,
          promise: promise
      }
  });
  </code></pre>
  
  <p>In the controller, I bind these variables to scope:</p>
  
  <pre><code>  $scope.statusPromise = statusFactory.promise;
    $scope.data = statusFactory.data;
  </code></pre>
  
  <p>And finally in the view I present the data</p>
  
  <pre><code>&lt;div cg-busy="statusPromise"&gt;
      {{data.var1}}
      {{data.var2}}
      ...
  &lt;/div&gt;
  </code></pre>
  
  <p>Now the data is being updated flawlessly, but cg-busy does nothing. I would expect the busy icon every time the $http call is being resolved. It works when I use the statusService directly in the controller. </p>
  
  <p>Is there some better way to do it? How can I expose some persistent promise from the factory so that it updates view on every new call?</p>