As user of websocketd, I want to filter events by headers

note(fblackburn)

acceptance (subscribe: xivo)
agentd (subscribe/publish: xivo)
amid (publish: xivo)
auth (publish: xivo)
calld (subscribe/publish: xivo) - nice example with MAP (routing-key/name) on_event()
call_logd (subscribe/publish: xivo) - durable
chatd (subscribe/publish: xivo)
confd (subscribe: wazo-headers, publish: xivo)
dird (subscribe/publish: xivo)
phoned (subscribe: wazo-headers)
plugind (publish: xivo)
plugind-cli (subscribe: xivo)
setupd (publish: xivo) - only for service-discovery
sysconfd (publish: xivo)
webhookd (subscribe: wazo-headers)
websocketd (subscribe: xivo)