Allow broadcast API calls

Changelog

• Require dependency to symfony/config component
• Handle both Individual and Broadcast Selligent API endpoints
• Adding helper to generate the XML document to broadcast complete HTML campaign

Breaking Change

The method Connection::open() has changed his signature. Now it will accept only an array who will contains a valid Mediapart/Selligent/Configuration tree.

To fix the breaking change, change your call from :

$config = [
    'login' => '***', 
    'password' => '***',
    'wsdl' => 'http://emsecure/?wsdl'
];

$connection = new Connection();
$client = $connection->open(
    $config['login'],
    $config['password'],
    $config['wsdl']
);

to :

$config = [
    'login' => '***', 
    'password' => '***',
    'wsdl' => 'http://emsecure/?wsdl'
];

$connection = new Connection();
$client = $connection->open($config);