Extract oauth_service.class config parameter

Author: igorw

src/Stack/OAuth/ContainerConfig.php

@@ -34,8 +34,10 @@ public function process(Pimple $container)
  return new StreamClient();
  });
 
+ $container['oauth_service.class'] = 'OAuth\OAuth1\Service\Twitter';
+
  $container['oauth_service'] = $container->share(function ($container) {
- return new Twitter(
+ return new $container['oauth_service.class'](
  $container['credentials'],
  $container['http_client'],
  $container['storage'],