code: public Promise call(String name, Tree params) {
  		return serviceInvoker.call(name, params, null, null, null);
  	}
docs: Calls an action (local or remote). Sample code:<br>
  <br>
  Tree params = new Tree();<br>
  params.put("a", true);<br>
  params.putList("b").add(1).add(2).add(3);<br>
  Promise promise = broker.call("math.add", params);
  
  @param name
  action name (eg. "math.add" in "service.action" syntax)
  @param params
  {@link Tree} structure (input parameters of the method call)
  
  @return response Promise