README and CHANGELOG update for release v0.8.1

Bump version to v0.8.1

Bump version to v0.8.0

Merge pull request commanded#36 from slashdotdash/feature/stream-subs…

…criptions

Subscriptions use Elixir streams to read events when catching up

Upgrade `fsm` dependency to v0.3.0 to remove Elixir 1.4 compiler warn…

…ings.

Release v0.7.3

Stream all events forward

Fixes commanded#34.

Include table of contents in README

Minor README update

Max capacity subscriptions catch up after all pending events ack

Subscriptions that are at max capacity should wait until all pending
events have been acknowledged by the subscriber being catching up with
any unseen events

Bump version v0.6.2

Update CHANGELOG and bump version to v0.6.1

Use `NaiveDateTime` for each recorded event's `created_at` property.

Bump version to v0.6.0