`lightningd` has an option --wallet that lets you supply a database dsn
string to connect to a sqlite3/postgres database that's hosted/stored
elsewhere.
This adds the `--bookkeeper-db` option which does the same, except for
the bookkeeping data for a node!
Note that the default is to go in the `lightning-dir` in a database
called `accounts.sqlite3`
Any file in this directory which is executable and whose name only
consists of alphanumeric characters, space, '.', '-' or '_' will be
automatically loaded when lightningd starts (unless suppressed with
commandline options).