Payment Actor Messages

applyCommands	Applies a list of commands to a Payment
charge	Registers a charge for a given amount. If the payment maps an external payment provider, this message should be called after the charge has been approved by the provider.
create	Creates a new Payment.
query	Queries the payment from the graph.
refund	Registers a refund for a given amount. If the payment maps an external payment provider, this message should be called after the refund has been approved by the provider.