title: ionic2 Refresher dose not show the pullingIcon and refreshingIcon
body: <p>i'm working on and angularjs2/ionic2 mobile app , and i need to integrate the refresher to make a pull to refresh from <a href="http://ionicframework.com/docs/v2/api/components/scroll/Refresher/" rel="nofollow noreferrer">this tutorial</a> .the refresher works fine but i cant get the icons to show's up ? here is my code :</p>
  
  <pre><code>&lt;ion-refresher (starting)="doStarting()"
               (refresh)="doRefresh($event, refresher)"
               (pulling)="doPulling($event, amt)" 
                pullingIcon="ion-loading-c"
                pullingText="pull to refresh" 
                refreshingIcon="add" 
                refreshingText="loading" &gt;
  &lt;/ion-refresher&gt;
  </code></pre>
  
  <p>and here is what i get : </p>
  
  <p><a href="https://i.stack.imgur.com/H4Lan.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/H4Lan.png" alt="enter image description here"></a></p>
  
  <p>can any one help me ?</p>