Usage:
----------------
The first thing required is to login

     $label = new Pakkelabels('api_user', 'api_key'); 

This will login and fetch the required token. 
The token is then automatically added to any subsequent calls. 

To see the generated token you can use:

    echo $label->getToken();

Examples:
----------------

    // Get all Post Danmark labels shipped to Denmark
    $labels = $label->shipments(array('shipping_agent' => 'pdk', 'receiver_country' => 'DK'));

    // Display the PDF for a specific label
    $base64 = $label->pdf(31629);
    $pdf = base64_decode($base64);
    header('Content-type: application/pdf');
    header('Content-Disposition: inline; filename="label.pdf"');
    echo $pdf;