[FEATURE] Paginate widget: throw Page Not Found Exception

This changes the behavior of the Paginate Widget to throw a
PageNotFoundException which results in a 404 HTTP status code
if a page number is requested which does not exist.

Previously the PaginateController would just display the last
page again.

Change-Id: Ie39f55b0454cf5b213acb14af470af17e8e67f3a