title: RescorerProvider filter element by tag
body: <p>Is it possible to create a RescorerProvider to filter out elements which are associated with a specific tag? Or should I implement an own model with relevant data as in the book "mahout in action" on page 79?</p>
  
  <p>Route: /recommend/?rescorerParams=sports<br>
  Push score of elements which are associated with tag sports</p>