Illumos #1884, #3028, #3048, #3049, #3060, #3061, #3093

1884 Empty "used" field for zfs *space commands
3028 zfs {group,user}space -n prints (null) instead of numeric GID/UID
3048 zfs {user,group}space [-s|-S] is broken
3049 zfs {user,group}space -t doesn't really filter the results
3060 zfs {user,group}space -H output isn't tab-delimited
3061 zfs {user,group}space -o doesn't use specified fields order
3093 zfs {user,group}space's -i is noop

Reviewed by: Garry Mills <gary_mills@fastmail.fm>
Reviewed by: Eric Schrock <eric.schrock@delphix.com>
Approved by: Richard Lowe <richlowe@richlowe.net>

References:
  illumos/illumos-gate@89f5d17b06fc4132c983112b24836a779a0ed736
  illumos changeset: 13803:b5e49d71ff0e
  https://www.illumos.org/issues/1884
  https://www.illumos.org/issues/3028
  https://www.illumos.org/issues/3048
  https://www.illumos.org/issues/3049
  https://www.illumos.org/issues/3060
  https://www.illumos.org/issues/3061
  https://www.illumos.org/issues/3093

Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1194