message: Update changelog for 0.8.1 release
  * Update changelog for release
  * Bump fluvio crate to 0.8.1
  * Remove commits in changelog w/o associated issues
  Bump down fluvio client crate to 0.8.0. 0.8.1 is being yanked. Wups.
diff: # Release Notes
  -
  -## Platform Version 0.8.1 -
  +## Platform Version 0.8.1 - 2020-05-03
  +* Use file name for the external commands (fixes #889) ([#1008](https://github.com/infinyon/fluvio/pull/1008))
  +* Fix Fluvio log directory on K8 ([#1043](https://github.com/infinyon/fluvio/pull/1043))
  +* Add RecordKey API for sending records without keys ([#985](https://github.com/infinyon/fluvio/pull/985))
  * Make Fluvio Client compatitble with WASM ([#1042](https://github.com/infinyon/fluvio/pull/1042))
  -* Improve replication logic([#1011](https://github.com/infinyon/fluvio/pull/1011))
  -
  +* Update Replication logic for SPU ([#1011](https://github.com/infinyon/fluvio/pull/1011))
  ## Platform Version 0.8.0 - 2020-04-27
  * Added Partitioner trait for assigning partitions based on record keys ([#965](https://github.com/infinyon/fluvio/pull/965))
  * Deprecated the `TopicProducer::send_record` method ([#965](https://github.com/infinyon/fluvio/pull/965))
  