LU-3950 lfsck: control LFSCK on all devices via single command

LU-3950 lfsck: control LFSCK on all devices via single command

Under DNE mode, it is more convenient for the administrator to control
the LFSCK (start/stop) on all the MDT devices via single command. Such
functionality is not only useful for DNE consistency verification, but
also for layout consistency (Phase II). It is also required for orphan
OST-objects scanning.

Test-Parameters: allwaysuploadlogs
Signed-off-by: Fan Yong <fan.yong@intel.com>
Change-Id: Ie0d4611f969e51b80faf27b52dbdaee41caf5187
Reviewed-on: http://review.whamcloud.com/7665
Tested-by: Jenkins
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>