LU-3950 lfsck: control all LFSCK nodes via single command (2)

LU-3950 lfsck: control all LFSCK nodes via single command (2)

The single command should work for not only layout LFSCK, but also for
other LFSCK components, such as namespace LFSCK, OI scrub on each node
and DNE LFSCK in the future.

Introduce another lfsck_start option "-o" for enable orphan handling.
Currently it is used for orphan OST-objects handling. When enable it,
the layout LFSCK will be triggered on all servers by default.

Code cleanup and more log information.

Signed-off-by: Fan Yong <fan.yong@intel.com>
Change-Id: Iaed9ee61d3d0fced32f9dd6b2a7f6663de6d2dc7
Reviewed-on: http://review.whamcloud.com/9257
Tested-by: Jenkins
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>