v0.9.0

• The package is now on PyPI
• Require at least beets v1.4.7
• Update album art in alternatives when it changes
• Python 3 support (Python 2.7 continuous to be supported)
• Support the format aliases defined by the convert plugin ('wma' and 'vorbis' with current beets)
• Bugfix: Explicitly write tags after encoding instead of relying on the encoder to do so
• Bugfix: If the formats config option is modified, don't move files if the extension would change, but re-encode