Fixed EZP-20455: eZUser::isLoggedIn does not correctly check user's stat...

Update ezuservisit when a user logout, to ensure eZUser::isUserLoggedIn getting correct status. Ref: 73ccec1d8fbf63b90f12a8c6c58228a4793541ea

It will set database ezuservisit.current_visit_timestamp to minus so the isUserLoggedIn will return false if the user already logout.