This isn't really part of the PR, but the `@standby_ips` var was causing us problems with a particular app.  The fact that it isn't fully free-form limits its usability.  It should be `<%= @standbys%>` (without the `/32`) or maybe even the whole `@standby_ips` concept should be replaced with a `@replication_perms` thing that passes through complete configuration lines.