Allow encryption of SQLite databases

[thunderbiscuit]

I don't know what's the best way to provide this and if it can be done without breaking the current API but allowing users to encrypt the db before writing to disk is a great feature to offer IMO. Opening this after speaking to folks at the summit.

cc @andreasgriffin

Also if it is possible already somehow (elegantly or hackily) I'll write something on the sqlite persitence page of the book.