Interface which drivers should implement.
connect function takes some driver specific name, value pairs
use to setup the database connection, and a database action to run.
requiredOptions lists all required options with a short description,
that is printed as help in the DBDirect program.
This driver passes its options through to HDBC. HDBC refers to http://www.postgresql.org/docs/8.1/static/libpq.html#LIBPQ-CONNECT for the meaning of the options.