OFBIZ-5793 Enhanced logic to run product subscription expiry service only once when the subscription expires:
a) augment the OFBiz data model with the new field: Subscription.expirationCompletedDate
b) modify the algorithm of runServiceUponSubscriptionExpiry to also check whether the expiry service has already run, by checking that expirationCompletedDate is null.
if expirationCompletedDate is null (and the other conditions are satisfied), run the service in SubscriptionResource.serviceNameOnExpiry and update the date/time into expirationCompletedDate
if expirationCompletedDate is not null, skip the expired subscription and move to the next

Thanks to Ivan Cauchi for the patch (slightly modified by me).


git-svn-id: https://svn.apache.org/repos/asf/ofbiz/trunk@1637535 13f79535-47bb-0310-9956-ffa450edef68