Support a flatfile backing store

[tcr]

trafficstars

This would allow you to run edit-text locally (for example) and store .ron files inside of Dropbox or a git repository. Not perfect (will Dropbox automatically try to do conflict resolution on utf-8 text?) but gives an alternative to storing an Sqlite database.

This would require abstracting out the storage component and making sure it works when shared across sync and server threads.

Some notes about fs flushing though: https://news.ycombinator.com/item?id=16573487