Save data persistently using a DB connection rather than writing to disk

[evanw555]

Writing to disk works so long as the bot is running locally. If this were to be hosted on some sort of remote virtual host, there's no guarantee that the file system will be persistent (it typically isn't).

We should use a PG client to write/read persistent data to make this more versatile.

[evanw555]

This has been resolved. Closing this, however the PG logic should be refactored so we can write tests