server: fix TestDirectPayment to issue refunds

Signed-off-by: Pierre-Alexandre Meyer <pierre@mouraf.org>
payment: relocate PaymentStates.xml

Cleanup as well the xml (remove chargebacks which don't have
state machines and remove invalid state transitions).

Signed-off-by: Pierre-Alexandre Meyer <pierre@mouraf.org>
payment: update to latest API

Deprecate RefundInfoPlugin for PaymentInfoPlugin.

Signed-off-by: Pierre-Alexandre Meyer <pierre@mouraf.org>
payment: update to latest API

Add stub for notifyPaymentOfChargeback.

Signed-off-by: Pierre-Alexandre Meyer <pierre@mouraf.org>