Add event APIs; refactor req/resp patterns; use real namespaces; many new RPCs; fix much gRPC lint; add and autogen docs.

The core services now export a `Subscribe` method which returns a filtered
stream of rdz.event.v1.Event objects.  These are designed to be portable to
a broker (e.g. Kafka, AMQP).  The `rdz.event.v1` package provides a generic
EventHeader type that creates an EventType enumeration, but it is up to
individual services to define their own Event objects and EventCode
enumerations.