When we create intermediate mount-points, make sure to set mountpoint=none
on them, to avoid confusion when user is looking at "zfs list" output
Add support for doing GELI encrypted ZFS mirrored disks, this
*should* work with GRUB, but it may prompt for the additional disk
passphrases during ZFS init of kernel boot
Fix which pc-sysinstall gets run via auto-install scripts. Don't
want to use old version in FreeBSD base
Update the warden to support jailed ZFS datasets. This can be
enabled by setting "allow.mount.zfs=1" on a jail. If this is
set, the jails ZFS dataset will be set to jailed mode, and
made visible to the jail. The user should also set
"enforce_statfs=0" and "allow.mount=1" on the jails flags as well,
for this to work properly.

Requested vie RedMine: #6495
Merge remote-tracking branch 'upstream/master'