(FACT 614) Add structured operatingsystem fact

This commit adds the 'operatingsystem_hash' structured fact,
which incorporates all operatingsystem-related facts into a
nested hash. Includes keys for the equivalents of
operatingsystem, osfamily, operatingsystemrelease,
operatingsystemmajrelease, and the lsb-based facts when available
on Linux and kfreebsd systems.