OpenZFS on OS X

Creating OpenZFS v2.0-rc2 releases for beta testers so we can find any obvious issues before release.

If you installed the earlier test pkg, you may want to delete /Library/Extensions/zfs.kext, and rebooting, before
installing other Open ZFS versions. As the earlier test has a KP on kextunload.

If you desire a different mac OS version, let me know.

Hmm we have a user who reports he gets metadata errors when trying to import his pools, rolling back works.

Need to figure out where this issue is comes from.