Make the Ratchet\App more configurable: no xdebug error, allow flashServer to not be constructed
I'm having to extend the Ratchet\App and squelch the error for local development (XDebug is off in production :) ) and also I'm not using the flash server so I'm turning that off too. Can these be made configurable instead?

```php
<?php

declare(strict_types=1);

namespace App\Broadcast;

use Psr\Log\LoggerInterface;
use Ratchet\App;
use React\EventLoop\LoopInterface;

class RatchetApp extends App
{
    /**
     * RatchetApp constructor.
     *
     * @param string        $httpHost
     * @param int           $port
     * @param string        $address
     * @param LoopInterface $loop
     */
    public function __construct(
        LoggerInterface $logger,
        string $httpHost = 'localhost',
        int $port = 8080,
        string $address = '127.0.0.1',
        LoopInterface $loop = null
    ) {
        @parent::__construct(
            $httpHost,
            $port,
            $address,
            $loop
        );

        $this->flashServer->socket->close();
        unset($this->flashServer);

        $logger->info('initialize RatchetApp', [
            'hostname' => $httpHost,
        ]);
    }
}

```