Added missing use statement for exception
Added an info_message option to the page view.
Also tidied up the logic for determining which tab is active and offered the option to add the active tab to the url.
Check the result of the publish handler - if it is a RedirectReponse object, then return it and allow the framework to perform the redirect.
Added an availablePublishHandlers method to the page method, which checks the permissions of the current user to determine which publish handlers should be offered to the user.
Added a message if there are no user online.