Change config file keys: (sorry)
  'client' => config for Guzzle client
  'service' => config for Guzzle service client (GuzzleClient)
  'description' => config for Guzzle service Description (Description)

Guzzle client can now be fed configuration values (client key above)

Add an XML ResponseLocation (xml-festivus) that returns data in a format
similar to the Httpful library.

Updated example httpbin.php service description.