This commit adds a postgresql::db type for convenience;
it mirrors the 'db' type from the mysql module, which
allows you to create a database instance and user plus
grant privileges to that user all in one succint
resource.
This commit also improves security in the following ways:
* Revoke "CONNECT" privilege from the 'public' role for
newly created databases; without this, any database
created via this module will allow connections from
any database user, and will allow them to do things
like create tables.
* Change to a 'reject'-based policy for dealing with
remote connections by the postgres user in pg_hba.conf.
Prior to this commit, if you tried to restrict access
to the postgres user by IP, the rule would simply not
match for disallowed IPs; then it would fall through
to the rule for "all" users, which could still match
and thus allow the postgres user to connect remotely.
