CRM-12679 - fixing paypal ipn test so it works with latest pp code.

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* CRM-12679: Paypal Express Recurring IPN not working?
  https://issues.civicrm.org/jira/browse/CRM-12679
Merge pull request #3469 from jmcclelland/paypal-ipn-test

CRM-12679 - fixing paypal ipn test so it works with latest pp code.
(causing tests to fail when you make changes is actually a good thing - it shows they care :-)