Updating govcloud endpoints.
Update SWF model with latest documentation
Update redshift regions
Bump jmespath version dep to 0.1.0
Add support for audio transcoding feature in Amazon Elastic Transcoder
Bumping version to 0.20.0
Merge branch 'release-0.20.0' into develop

* release-0.20.0:
  Bumping version to 0.20.0