Release v0.17.0

Release v0.16.0

Release v0.15.1

Release v0.15.0

Only notify pending events when out of order event received

CHANGELOG for release v0.12.0

Include upgrade advice for release v0.14.0 in CHANGELOG

Minor markdown formatting

Subscriber can confirm receipt an event by its `event_id` or `stream_…

…version`

Depending upon whether it is an all streams or single stream subscription.

Setting `event_type` field described in README

Fixes commanded#61.