Add support AMQP

[peter-gribanov]

fix #11

Configure queue:

use GpsLab\Domain\Event\Queue\Subscribe\AMQPSubscribeEventQueue;
use GpsLab\Domain\Event\Queue\Serializer\SymfonySerializer;
use PhpAmqpLib\Connection\AMQPStreamConnection;
use Symfony\Component\Serializer\Serializer;
//$connection = new AMQPStreamConnection('localhost', 5672, 'guest', 'guest'); // AMQP connection
//$channel = $connection->channel();
//$symfony_serializer = new Serializer(); // Symfony serializer
//$logger = new Logger(); // PSR-3 logger
$queue_name = 'article_queue';
$format = 'json'; // default: predis
// you can create another implementation of serializer
$serializer = new SymfonySerializer($symfony_serializer, $format);
$queue = new AMQPSubscribeEventQueue($channel, $serializer, $logger, $queue_name);

Subscribe to the queue:

use GpsLab\Domain\Event\Bus\ListenerLocatedEventBus;
use GpsLab\Domain\Event\Listener\Locator\DirectBindingEventListenerLocator;
$locator = new DirectBindingEventListenerLocator();
$bus = new ListenerLocatedEventBus($locator);
$handler = function(ArticleRenamedEvent $event) use ($bus) {
    $bus->publish($event);
};
$queue->subscribe($handler);

You can unsubscribe of the queue:

$queue->unsubscribe($handler);

Make event and publish it into queue:

$event = new ArticleRenamedEvent();
$event->new_name = $new_name;
$queue->publish($event);

[coveralls]

Coverage remained the same at 100.0% when pulling a6e62a4 on peter-gribanov:amqp into 3db48d8 on gpslab:master.