mnttab cache from FreeBSD

Brings over the mnttab implementation from FreeBSD.
Bug fix for com.apple.ignoreowner reversed logic.
Bug Fix for binary numeric properties not showing up in zfs get.
Adds com.apple.browse and com.apple.ignoreowner to the list
of binary numeric properties in get_numeric_property.

Support for "temporary" mount options strings passed in by user
still needs to be added.