LU-1565 disabling ELC through procfs

LU-1565 disabling ELC through procfs

adding a possibility to disable ELC through procfs, for test purposes only.

Change-Id: I45153d67f325bd464943c8f618d5c86dd663166e
Reviewed-by: Andrew Perepechko <Andrew_Perepechko@xyratex.com>
Reviewed-by: Alexander Zarochentsev <Alexander_Zarochentsev@xyratex.com>
Signed-off-by: Vitaly Fertman <vitaly_fertman@xyratex.com>
Xyratex-bug-id: MRP-477
Reviewed-on: http://review.whamcloud.com/3188
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Mike Pershin <tappro@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>