LU-1303 lod: directories to inherit default striping

LU-1303 lod: directories to inherit default striping

on creation. the patch adds sanity check on default striping
being set by an user.

Signed-off-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Change-Id: I4142a2189b00158454c7525939a9c6019a5e874a
Reviewed-on: http://review.whamcloud.com/4056
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: wangdi <di.wang@whamcloud.com>
Reviewed-by: Mike Pershin <tappro@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>