Merge branch 'master' of github.com:thephpleague/omnipay-authorizenet into xml-api

Conflicts:
	src/Message/AIMRefundRequest.php
	src/Message/AIMResponse.php
	tests/Message/AIMRefundRequestTest.php
	tests/Message/AIMResponseTest.php

Author: anush

src/Message/DPMResponse.php

@@ -59,6 +59,9 @@ class DPMResponse extends AbstractResponse implements RedirectResponseInterface
         'x_email_customer',
 
         'x_delim_data',
+
+        // Custom omnipay field.
+        'omnipay_transaction_id',
     );
 
     /**