The suggested default is better, following peer review. Though some
changes will probably need to be made once we decide how to handle
system only backups.
Not just esthetic, for some reason ansible refused to run with '-'
somewhere and I just could not find where, changing variables and
tags to use '_' fixed it. It's more consistent anyway.
This makes it a bit more annoying to define default hosts for
multiple machines, but it's not that bad and it's better than not
being able to define heterogeous ports.
