LU-3285 lfs: add parameter for Data-on-MDT file

LU-3285 lfs: add parameter for Data-on-MDT file

Add --layout|-L parameter to lfs setstripe to create
file with data on MDT layout.
Add DoM size limit at LOD level - lod.dom_stripesize
parameter.

Signed-off-by: Mikhail Pershin <mike.pershin@intel.com>
Change-Id: Ib97142cc23c75e890dc619c14e5ffb3f3c47cda5
Reviewed-on: https://review.whamcloud.com/28012
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>