code: public static RequestToken fetchData(String id, BaasHandler<JsonObject> handler){
          return fetchData(id, RequestOptions.DEFAULT, handler);
      }
docs: Asynchronously retrieves named assets data,
  If the named asset is a document, the document is retrieved
  otherwise attached data to the file are returned.
  This version of the method uses default priority.
  
  @param id the name of the asset
  @param handler an handler that will be handed the response
  @return a request token