Workaround for RasPi selecting jack server.
Fixed long line Flake8 warning.
travis: Update tox env names
docs: Add v0.20 changelog
Merge pull request #801 from arjunrn/develop

raspi: Workaround for RasPi selecting jack server.
audio: Link to context of why we demote jack sinks
doc: Add changelog entry for jack sink fix
Merge branch 'develop' into feature/audio-prep-work-for-gapless