LU-7991 quota: project quota against ZFS backend

This patch enables the project quota feature against ZFS
backend. The project quota patch for ZFS itself will be
landed via https://github.com/zfsonlinux/zfs/pull/6290.
Such patch may be released via zfs-0.7.x (x >= 5).

This patch also cleanup the quota logic for ZFS backend
and sanity-quota.sh

Signed-off-by: Fan Yong <fan.yong@intel.com>
Change-Id: Ic488efe19a6e34a3615811f79fb9ea7954ad9263
Reviewed-on: https://review.whamcloud.com/27093
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Wang Shilong <wshilong@ddn.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>