Use new demo GeoServer location

demo.opengeo.org currently redirects to demo.boundlessgeo.com, so this
change makes it so the new location is used directly.

examples/wms-tiled.js

@@ -12,7 +12,7 @@ var layers = [
   new ol.layer.Tile({
     extent: [-13884991, 2870341, -7455066, 6338219],
     source: new ol.source.TileWMS(/** @type {olx.source.TileWMSOptions} */ ({
-      url: 'http://demo.opengeo.org/geoserver/wms',
+      url: 'http://demo.boundlessgeo.com/geoserver/wms',
       params: {'LAYERS': 'topp:states', 'TILED': true},
       serverType: 'geoserver'
     }))