title: Angular ionic badge count not updating
body: <p>I am new to angular and believe i am not fully understanding the digest cycle. 
  I am trying to update a badge count in a ion-tab.(using ionic)</p>
  
  <p>"ion-tab"</p>
  
  <pre><code>&lt;ion-tab title="Requests" badge="data.badge" ng-controller="RequestTabCtrl" badge-style="badge-assertive" icon-off="ion-pull-request" icon-on="ion-pull-request" href="#/tab/requests"&gt;
  &lt;ion-nav-view name="tab-requests"&gt;&lt;/ion-nav-view&gt;
  </code></pre>
  
  <p></p>
  
  <p>I have written a factory that will store and array. this array is updated through socket.io</p>
  
  <p>"notifications factory"</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>.factory('notifications',function(){
    var list = [];
    return{
      all: function(){
        return list;
      },
      add: function(data){
        list.push(data);
      },
      length: function(){
          return list.length;
      }
    };
  });</code></pre>
  </div>
  </div>
  </p>
  
  <pre><code>.controller('RequestTabCtrl',function($scope,notifications){
    $scope.data = {
      badge : notifications.length()
      };
  });
  </code></pre>
  
  <p>My problem is that the badge count is not updating when the notifications array is updated through socket.io. I have checked that the array is being updated. In fact i can console log the array length and can see it it changing. Also i have set a scope variable in the ion-tab's child io-nav-view and as a result can see the expression {{requests.length}} be updated in this view.</p>
  
  <pre><code>.controller('RequestsCtrl', function($scope,notifications) {
    $scope.requests = notifications.all();
  })
  </code></pre>
  
  <p>I have tried $watch(in RequestTabCtrl) on notifications.length. i have tried calling $apply(in RequestTabCtrl) which results in a $digest already in progress. I have tried $timeout and see no positive result (in RequestTabCtrl and the factory length function). Help will me much appreciated. </p>