Add method 'add option' to easily extend options for a parameter that is already present

[malc0mn]

Something like:

<?php
$backend = Backend::create('servers')
            ->addServer('server1', '127.0.0.1', 8000, ['maxconn', 32])
;
$backend->addOption('server1', 'backup');

// OR...

$backend->addOption('server1', ['check', 'backup']);