Code cleanup.
Add process initiator.
Example process manager in test.
Move pubsub into its own package and split it into files.
Introduce PositionUpdate on pubsub.
Allow subscription for more than one topic.
Allow to modify subscriptions.
EventBusConfig directly handles ProcessManager->Topic mapping.
Implement subscription setup in InitiatorActor.
Cleanup ProcessInitiator.
Make topic subscriptions non-hierachical.