title: progress notifications in ECMAScript Promise
body: <p>We're using <code>ECMAScript 6 promises</code>.</p>
  
  <p>We need to implement progress notifications to the end-user (this is pure UX requirement). I know that other promise frameworks (<code>Q promise</code> library, for ex.) allows that. </p>
  
  <p>How can we adopt some kind of progress indication <strong>most elegantly</strong>? </p>
  
  <p>Or should we <strong>migrate</strong> to a different framework? 
  (I don't know how to estimate the effort of the latter)</p>