add 'connectionParams' in register()

I used connectionParams for my production server

And `app/config/elsaticsearch.php` : 

    return array(
        
        // connexion à searchbox.io
        'hosts' => [
            'your_hosts'
        ],
        'connectionParams' => [
            'auth' => [
                'site',
                'xxxxxxxxxxxxxx',
                'Basic' 
            ]
        ]
    );