Don't spit errors on windows

The stderr redirection to `/dev/null` makes windows emit errors on every
single facter/puppet run. This simply redirects to `nul` instead when
running on windows family.
Merge pull request #41 from binford2k/dont_barf_errors_on_windows

Don't spit errors on windows
0.3.0 prep
Merge pull request #42 from mhaskel/0.3.0-prep

0.3.0 prep