Nickname parameter for action 'usergroups' is not removed with fancy urls

When fancyurls are activated, the nickname parameter is moved to the front of the URL: „http://identi.ca/adrianlang/groups“. To date, common_fancy_url does not remove the nickname, so it looks like „http://identi.ca/adrianlang/groups?nickname=adrianlang“.

Proposed new version in lib/util.php:
{{{
case 'usergroups':
$nickname = $args['nickname'];
unset($args['nickname']);
return common_path($nickname.'/groups' . (($args) ? ('?' . http_build_query($args)) : ''));
}}}