Integrate recent changes in bookstore demo
Integrate recent changes in bookstore demo

* Make use of the new append syntax which allows appending of multiple
widgets.
* Change obsolete "createPage" method invokation to "create".

Change-Id: Ie786e0b227281ab44b18a7c7fa3575686aeb54b0

moham3d/tabris-js,softnep0531/tabrisjs,pimaxdev/tabris,mkostikov/tabris-js,pimaxdev/tabris,moham3d/tabris-js,paulvi/tabris-js,mkostikov/tabris-js,eclipsesource/tabris-js,eclipsesource/tabris-js,eclipsesource/tabris-js,softnep0531/tabrisjs