Export scrobble history to JSON data store

[jwflory]

Summary

Support JSON format for exporting history from a platform

Background

Currently, last2libre writes data out to a text file separated by tabs and new lines. It would be cleaner to offer support for JSON export. This puts the data into a more easily programmable format for other developers to use the data for their wishes.

Additionally, the importer module can be updated to read in the JSON instead of doing that step manually like it is now.

Details

Write all entries to a dict where each key represents a unique listen. All the values in the dict represent different metadata pieces. At the end of the import process, write the dict out as JSON instead of a text file.

Ideally, if all text file functionality can be deprecated, I consider this a major win.

Outcome

Support data export format to improve ease of use for external developers / users