Replace sqlite database with append only file

[Alextopher]

This is a fairly major change, I'll add some testing soon.

I've been thinking that using a sqlite database isn't the best strategy for COSI project since we don't have good rollback/backup cabablities.

Using an event log means we can recreate the database from any previous state, just by removing the last N lines.

[Alextopher]

Please don't merge until we give #6 a chance