AlertManager service does the wrong thing if the Ajax request will terminate with a redirect

When invoking the AlertManager methods during an Ajax request, the AlertManager may not persistently store new Alerts (those that are not of persistent duration), as it expects that they will instead be transferred in the response down to the client for immediate display. However, in the case where a redirect is sent to the client (i.e., returning a page class or instance from the Ajax event handler method), the messages are not displayed on the new page since they were not stored between requests.

The AlertManager should configure things so that Alerts are added to the response and to the AlertStorage SSO and, if the Alerts are in fact sent to the client, cleared from the SSO as well.