title: kinetic js group position is not correct when dragging
body: <p>I am trying to create group object that include text,image .
  I want to get right position(x,y) when dragging the group object.
  Now i get minus value {x:-26,y:-18} like that.</p>
  
  <pre><code> var text2=new Kinetic.Text({
          x: 40,
            y: 125,
          text: 'Time:4:20',
          fontFamily: 'Calibri',
          fontSize: 12,
          padding: 5,
          fill: 'red',
          draggable: false
        });
      var group = new Kinetic.Group({
                      width:94,
                      height:45,
                      draggable: true
                      });
                     group.on('dragend', function() {
                            alert("X:"+group.getAbsolutePosition().x+"Y:"+group.getAbsolutePosition().y);
                          });
   group.add(text2);
   layer.add(group);
  stage.add(layer);
  </code></pre>