Persist IndexedDB to disk.

[ngokevin]

https://github.com/dumbmatter/fakeIndexedDB says only in-memory and Functionally, it works exactly like IndexedDB except data is not persisted to disk.

Also in Supercraft, the sites don't seem to be fetching from IndexedDB to populate the load list. Need to investigate.

[avaer]

Yes, it was a stopgap to get the api working. localStorage should persist.

That probably means we should introduce the notion of a profile dir too.