travis: Update installation steps
tox: Add tox config
travis: Use tox to run tests
Make artists order stable (aka sorted)
Work with None as default track_no in Mopidy 0.20
readme: Use shields.io badges
Ensure all files are packaged on PyPI
Release v1.1.1
Merge tag 'v1.1.1' into debian

Release v1.1.1
debian: New upstream release