title: 3-way bind date format with AngularJS and Firebase
body: <p>In all my projects I'm running into the same problem trying to figure out what the best way is to have a proper way of binding a timestamp (date) with my view and Firebase. I'm currently using the <code>md-datepicker</code> directive from Angular-Material but unfortunately this directive only supports a date object, and because Firebase won't accept a date object the value will always be empty.</p>
  
  <p>In several projects I'm storing epoch timestamps in milliseconds in Firebase. Is there any possibility to have a proper 3-way data binding with epoch timestamps in Firebase and the <code>md-datepicker</code>?</p>
  
  <p>Thanks!</p>