Pull the Subscription ID from the 2nd item in the reference string

At some point the CyberSource gateway was updated to pull it from the 
6th item, but our records are still storing it on the 2nd.

Probably update/migrate all of our strings soon to make them match 
ActiveMerhant master.

Author: jeffschuil

lib/active_merchant/billing/gateways/cyber_source.rb

@@ -618,7 +618,9 @@ def add_subscription(xml, options, reference = nil)
 
         xml.tag! 'recurringSubscriptionInfo' do
           if reference
-            subscription_id = reference.split(';')[6]
+            # subscription_id = reference.split(';')[6]
+            # our subscription/request id has historically been the second item
+            subscription_id = reference.split(';')[1]
             xml.tag! 'subscriptionID',  subscription_id
           end