Mopidy-local

- Move parts of the scanner functionality from Mopidy. (19)

- Require Python >= 3.7. (PR: 10)

- Require Mopidy >= 3.0.0a5. (PR: 10)

- Require Pykka >= 2.0.1. (PR: 10)

- Update project setup. (PR: 10)

- Merge Mopidy-Local-SQLite into Mopidy-Local (PR: 10)

- Merge Mopidy-Local-Images web extension into Mopidy-Local. (PR: 10)

- Remove support for pluggable libraries, remove the JSON library storage,
and use SQLite instead. (PR: 10)

Initial release which extracts the Mopidy-Local extension from Mopidy core.

This is an alpha release because it depends on the pre-releases of Mopidy 3.0.