Remove unnecessary parametres from logout link in menu block

For now, logout link in menu block looks like this:
`ucp.php?mode=logout&sid=90e43a7fc3f444857426fa8b45deef22&redirect=./activitypage.php`, but `&redirect=./activitypage.php` part is unnecessary. It should be removed.

http://phpbbsocialnetwork.com/viewtopic.php?f=44&t=4735