Create Design Proposal for Event Listeners

[tripott]

Create a design proposal for Event listeners for errors and other messages from the adapters to the core.

• Which events are an adapter allowed to emit?
• What is the event message format
• What response (if any) is elicited from the core? The unhealthy event causes re-bootstrapping, data write just propagates to listeners
• How do we expose subscribing to events in the hyper config?