Changed operating system check to validate osfamily

Due to the large number of RHEL clones changed the operating system
check to look at osfamily rather than operatingsystem facts. Also did
the same for debian to be consistant.

For instance on Scientific Linux you would get the following somewhat
confusing error.

Unsupported osfamily: RedHat operatingsystem: Scientific, module redis
only support osfamily RedHat and Debian
Merge pull request #29 from george-b/osfamily

Changed operating system check to validate osfamily