LU-1866 misc: fix some issues found during LFSCK

1) Test scripts issues for sanity.sh and sanity-scrub.sh

2) Incorrectly use open flag 'MDS_OPEN_OWNEROVERRIDE" for
   permission check for set_attr.

3) Other code clean, such as mdt_body, md_op_spec, wiretest.

Signed-off-by: Fan Yong <fan.yong@intel.com>
Change-Id: I52fbfe8481e35edba75e8fe7e0ab2fec094eabae
Reviewed-on: http://review.whamcloud.com/5046
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: wangdi <di.wang@intel.com>