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.
Update javadocs for PaymentGatewayQueries
Merge branch 'EVENT-24' into EVENT-64
Add ability to save and reference paymentGatewayId
- rename previous paymentGatewayId to paymentGatewayUserSetId
Remove `PaymentGatewayEntity`
 and merge the logic all into `ConferenceEntity`
Fix broken injection points
 and a broken query
Ensure saving w/o a paymentGatewayKey doens't blow away old previously saved key
whitespace (to tabs)
Remove constructor injection and inject fields
whitespace (to tabs)
Merge pull request #240 from CruGlobal/EVENT-64

Correct the way that PaymentGatewayEntities are saved.