[amqp] fix config options.

[makasim]

fixes php-enqueue/enqueue-dev#309

[cedricmagne]

Same error.
Therefore if we change config node we need to change setting node in setting.xml
I suggest to change array keys in Enqueue/Enqueue/Helper/Data.php line 133

/**
 * @return array
 */
public function getRabbitMqAmqpConfig()
{
    return ['rabbitmq_amqp' => [
        'host' => Mage::getStoreConfig('enqueue/rabbitmq_amqp/host'),
        'port' =>  (int) Mage::getStoreConfig('enqueue/rabbitmq_amqp/port'),
        'user' => Mage::getStoreConfig('enqueue/rabbitmq_amqp/login'),
        'pass' => Mage::getStoreConfig('enqueue/rabbitmq_amqp/password'),
        'vhost' => Mage::getStoreConfig('enqueue/rabbitmq_amqp/vhost'),
        'lazy' => (bool) Mage::getStoreConfig('enqueue/rabbitmq_amqp/lazy'),

    ]];
}

Thanks,