Make zpool_version fact handle feature flags
Split out the zpool_version fact
Vendor zpool_version from puppetlabs-facter

Don't confine to Linux any more, just make sure we have the zpool
command.
Split out zfs_version fact, update for any OS
Merge branch 'feature/featureflags' into devel
Merge branch 'devel' of github.com:geoffdavis/puppet-zfsonlinux into devel