title: How to change the label from back button in Ionic 2?
body: <p>With the code:</p>
  
  <pre><code>&lt;ion-navbar *navbar&gt;
  &lt;/ion-navbar&gt;
  </code></pre>
  
  <p>the back button is enabled. But I need to customize it (the icon or the label). Is it possible?
  Can't find anything in the docs/api.</p>