Patch for SHA256 support for OmniPay MIGS

gistfile1.txt

--- AbstractRequest.php.2	2016-09-21 19:45:07.846345749 -0400
+++ AbstractRequest.php	2016-09-21 19:46:47.049424061 -0400
@@ -67,6 +67,9 @@
 
         $hash = null;
         foreach ($data as $k => $v) {
+            // Skip vpc_ keys that are not included in the hash calculation
+            if(in_array($k, array('vpc_SecureHash', 'vpc_SecureHashType'))) continue;
+
             if ((strlen($v) > 0) && ((substr($k, 0, 4)=="vpc_") || (substr($k, 0, 5) =="user_"))) {
                 $hash .= $k . "=" . $v . "&";
             }