Add a payment to the mock DB for functional tests
Add null check here so that '****null' doesn't get displayed.
 - Also add serializable ID
Support returning more than one payment per conference.  Multiple payments will be sorted by transaction date time (oldest to newest)
`Registration` now contains a list of `Payment` objects, and a method to add a list of JPA style `PaymentEntity` objects all at once.
bracketology
When fetching a regstration through either `RegistrationResource`'s getRegistration or `ConferenceResources` getRegistrations(), also fetch payments for those registrations and attach them.
Write functional tests for pulling down payment information along with registration.
Give the functional tests a registration with multiple payments for testing
Adding a test for a registration with multiple saved payments
Merge pull request #66 from CruGlobal/get-payments-with-registration

Get payments with registration