Make the class autoloadable using the buildin Composer autoloader

Created by: christiaan

Register namespace with Composer so the autoloader works.

After adding "ulrichsg/getopt-php" to your composer.json you can now do the following in your main package.

// Require the composer autloader
require_once __DIR__.'/../vendor/.composer/autoload.php';
use Ulrichsg\Getopt;
new Getopt();