function outputUsers($dbAdapter)
{
    $gate = new TravelUserDetailsTableGateway($dbAdapter);
    $result = $gate->findAll();
    echo '<div class="list-group">';
    foreach ($result as $row) {
        echo utf8_encode('<a href="single-user.php?id=' . $row->UID . '" class="list-group-item">' . $row->FirstName . ' ' . $row->LastName . '</a></li>');
    }
    echo '</div>';
}