title: Angular2 i18n for placeholder text
body: <p>Is there a way to translate the placeholder text for an input text field using Angular 2's i18n?</p>
  
  <p><code>
  &lt;input placeholder="hello world" i18n&gt;
  </code></p>
  
  <p>I don't see anything in the documentation about this: 
  <a href="https://angular.io/docs/ts/latest/cookbook/i18n.html" rel="noreferrer">https://angular.io/docs/ts/latest/cookbook/i18n.html</a></p>