Issue #68 raised a valid problem: The postfix formula is using
the osmap.yaml file incorrectly. It is being used to filter on
the os grain but should instead be filtering on os_family
to correctly account for Red Hat/CentOS similarities.
PR #69 did the fix in a complex way as it only moved parts of the os
mapping into the os_family mapping.
This is a much simpler fix, as it just renames the file and uses
it as a os_family map, which it actually is.
If we really need to differentiate between os flavors inside the
os_family at a later date, we can then add a lookup on the os grain.
No need to complicate manners now.
