LU-3999 hsm: Rename several HSM files in /proc for MDT.

LU-3999 hsm: Rename several HSM files in /proc for MDT.

Some files in /proc, available for MDT are misnamed. This could be
incoherent or troublesome for sysadmins. This patch renames them.

`actions' is used when refering to HSM requests stored in MDT llog.
`active_requests' is used when refering to HSM requests currently
being handled by a copytool, on an agent node.

Also rename some HSM variable names and functions to have them
matching proc file names more consistently.

sanity-hsm tests have been updated accordingly.

Signed-off-by: Aurelien Degremont <aurelien.degremont@cea.fr>
Change-Id: If2b5c24e06d480554040d8f69b09236e0ddd98e9
Reviewed-on: http://review.whamcloud.com/7740
Tested-by: Hudson
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Faccini Bruno <bruno.faccini@intel.com>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>