By adding a 'type' field to the operatingsystem record and then managing this field manually we can make Rails cast the record to the required family class.

Fixed for 1.5
Tests work

Added OS before_filter to deduce the family, if not set
OS DB entries can now contain a null type
@@families promoted to Operatingsystem::FAMILIES
Included mods suggested by Ohad

Rebased
Centralized Family name and os membership list into a single hash
Added test in unattended controller that detects if a os has no family
simplified deduce_family
tests pass