staging/lustre/mdt: HSM on disk actions record

HSM coordinator memorizes all actions in a llog
This patch implements the methods needed to create
update display these records.

Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-3339
Lustre-change: http://review.whamcloud.com/6529


Signed-off-by: JC Lafoucriere <jacques-charles.lafoucriere@cea.fr>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Peng Tao <tao.peng@emc.com>
Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>