Expose structured events

[eulerfx]

Currently, Kafunk logs a good deal of information to STDOUT, and the events are structured loosely as follows:

type Evt =
  struct
    val name : string
    val data : Map<string, obj>
    val msg : string
  end

But the structure isn't explicit and there isn't an easy way to subscribe to specific events. We should consider the more appropriate way to expose these events.

• Consider using IObservable
• Consider using Loggary

[eulerfx]

In addition, this should allow configuration of the severity level associated with an event.