bump ari version: fix DeviceStateChanged event

dep update

events without keys should emit warning log

undeprecate rid

ci: update goreleaser config

implement externalMedia channel creation

accept empty playback IDs

use explicit goreleaser version

travis: encore GO111MODULE

Convert to go modules; add ARI status check

All NATS responders now check the ARI client to make sure it is
connected before responding.

Fixes CyCoreSystems#25