Merge pull request #97 in ASAPO/asapo from feature_ASAPO-111-acks to develop

* commit 'bee88c9b':
  fix test
  producer retrieves stream info
  start providing last id via producer
  fix using non-positive ids
  refactor, add integration tests
  refactor, implement last_ack_id
  return nacks
  update hasicorp pack to latest versions
  implement ack function
  started working at acks
  refactor
  create position pointer if not exist on each get_next request