Use ol.Collection#extend in examples

This commit changes the examples to using ol.control.defaults().extend to extend the collection of controls. This is in preparation for a future commit that will remove the 2nd argument to ol.control.defaults. The same is done for ol.interaction.defaults.

examples/mouse-position.js

@@ -20,7 +20,7 @@ var mousePositionControl = new ol.control.MousePosition({
 });
 
 var map = new ol.Map({
-  controls: ol.control.defaults({}, [mousePositionControl]),
+  controls: ol.control.defaults().extend([mousePositionControl]),
   layers: [
     new ol.layer.TileLayer({
       source: new ol.source.OSM()