Added sudo_user for postgresql_users/database commands. Removed host opt...

Hi!

Bugfix here: login_host attribute is used to specify credentials for postgresql_user module, not for limiting access for newly created user.

And I added sudo_user option for postgresql_user/postgresql_database modules because it makes possible to use peer authorization in pg_hba.conf (and doesn't affect users who don't use it).

By the way, shouldn't this role create the same pg_hba.conf as in original ubuntu package? I think that would be the less surprising behavior.

P.S. Thanks for sharing this role!