Added creation of db, user, pg_hba.conf

Added parameters for db_name, db_username, db_password and
client_ip.  When these values are passed a PostgreSQL user is
created then a database is created owned by that user.

The pg_hba.conf file is created based on the parameters
Merge pull request #6 from letterj/modpostconf

Added creation of db, user, pg_hba.conf