API change for PaymentStatus -> TransactionStatus

API change for PaymentStatus -> TransactionStatus (2)
Rework Payment exception handling for state machine operation and interraction with thread dispatcher code.

The state machine code rely on OperationResult and OperationException to correctly route to the next state so it crucial to
throw correct exception to land in the correct state.
Merge branch 'master' of github.com:killbill/killbill