Allow removal of all explicit equivalences

If no explicit equivalences are provided, equivalences
should still be written, thereby removing any existing
explicit equivalences.
Merge pull request #160 from atlasapi/update-all-explicit-equivs

Allow removal of all explicit equivalences
Merge pull request #159 from atlasapi/kafka

Integrate Kafka
remove AbstractMessage
remove AbstractMessageConfiguration
add schedule update message
send message on schedule block update
Merge branch 'schedule-udpate-msg' into stage

* schedule-udpate-msg:
  send message on schedule block update
  add schedule update message
  remove AbstractMessageConfiguration
  remove AbstractMessage
  Allow removal of all explicit equivalences