fixed namespaces issue with composer

Hi Francis,

I started to play around with Paradox using composer. The require section looks like this:

    "require": {
        "triagens/arangodb": "dev-devel",
         "f21/paradox": "dev-master"
     }

Problem: The Paradox classes are not found through the autoloader generated by composer.
Reason: composer generates a file vendor/composer/autoload_namespaces.php. This points to the wrong path, in the old version it was 
    'Paradox' => array($vendorDir . '/f21/paradox/Paradox'),

I adapted the composer.json so it's now

    'Paradox' => array($vendorDir . '/f21/paradox'),