Correct the way that PaymentGatewayEntities are saved.

- A new paymentGatewayId is created each time the conference is parsed to a PaymentGatewayEntity. Because of this,
- the PaymentGatewayEntities were not being updated correctly. Instead of updating by UUID, the PGE is now updated by
- PaymentGatewayId (String)

This is now tested as part of the UpdateConference test.
fixed, well kind of.  the file had a mix of spaces and tabs. i converted the whole file to tabs, which has been the default for the project.  if you prefer it, i can probably dissect which lines should be which for a cleaner review.  Your call