Restructure namespace to make it easier to distribute separate packages in the future

Author: amacneil

tests/bootstrap.php

@@ -2,6 +2,8 @@
 
 error_reporting(E_ALL | E_STRICT);
 
-// include the composer autoloader and add our tests directory
+// include the composer autoloader
 $autoloader = require __DIR__.'/../vendor/autoload.php';
+
+// autoload abstract TestCase classes in test directory
 $autoloader->add('Omnipay', __DIR__);