SSH tunneling

[tconbeer]

Need to think through whether this is an adapter feature or a harlequin feature. Maybe it's a library that adapters can use.

Would be nice to provide CLI options for configuring an ssh tunnel, and then intercept/rewrite the host/port/etc options passed through to the adapter.

See:

https://stackoverflow.com/questions/22046708/psycopg2-access-postgresql-database-on-remote-host-without-manually-opening-ssh