LU-7093 mdt: Remote operation permission check

LU-7093 mdt: Remote operation permission check

Only do permission check for migrate, create striped (remote)
directory, and set default LMV stripeEA for directory.

For non-administrators, only if their gid match
enable_remote_dir_gid (under /proc) or
enable_remote_dir_gid = -1, then they can do these above 3
operations.

Signed-off-by: wang di <di.wang@intel.com>
Change-Id: Id103ddd4dbf4a1901a32b599639037de8ce58e4a
Reviewed-on: http://review.whamcloud.com/16286
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>