Save all hosted and played games

[ekolis]

The lists of games could be saved into a JSON file (maybe the config file) so that they will always be accessible, even when PBW chooses to hide hosted games because they're not in need of processing.

Then we'll need to add the ability to forget/delete a game.

This would allow for #9 and #13.

We'll also need to filter hosted games to those actually in need of processing when going to process a turn.