title: Return empty json on null in WebAPI
body: <p>Is it possible to return { } instead of null  when webApi returns a null object? 
  This, to prevent my user from getting errors while parsing the response. And to make the response a valid Json Response?</p>
  
  <p>I know that i could be setting it everywhere manually. That when null is the response, an empty Json object should be returned. But, is there a way to do it automaticly for every response?</p>