Code review comment for lp:~pjdc/charms/trusty/postgresql/nagios-additional-servicegroups

We should probably just allow nagios@localhost to authenticate without a password. The account will still need to be created manually on the master when using manual replication, but it means we don't also need to sync the nagios user's password around. But no need to block this branch on that refactoring.

The changes look good. Ta.