Replace lsbmajdistrelease fact check with operatingsystemmajrelease

This relates to #58.  I do not like the dependencies pulled in by 'redhat-lsb' so using the `lsbmajdistrelease` fact is not an option in this case.  The `operatingsystemmajrelease` fact is simpler and requires no package dependencies.  AFAIK it's in all the stable versions of Facter (1.7 and 2.x).