Use operating system fact, don't depend on LSB

[cryptomeme]

This could resolve #51.

The 'lsb*' facts need the tool lsb_release, which on my CentOS 6 system was not present and had some non-trivial dependencies. The operatingsystemmajrrelease is equivalent per https://docs.puppet.com/facter/2.4/core_facts.html#operatingsystemmajrelease