CP-6337: Added multipath.conf manipulator

This script is a basic multipath.conf to add and remove
WWIDs in the blacklist_exceptions section

Signed-off-by: Germano Percossi <germano.percossi@citrix.com>
Reviewed-by: Keith Petley <keith.petley@citrix.com>
CP-6337: Added locking mechanism to wwid_conf

Signed-off-by: Germano Percossi <germano.percossi@citrix.com>
Reviewed-by: Keith Petley <keith.petley@citrix.com>
CP-6337: Use reconfigure and wwid utils

This patch ensure the new mechanism for explicit multipath
mapping is active.
The corresponding patch in dm-multipath can be removed.

Signed-off-by: Germano Percossi <germano.percossi@citrix.com>
Reviewed-by: Keith Petley <keith.petley@citrix.com>
CP-6337: Ensure multipath kernel modules are present

Once started the multipath daemon does not load the needed
kernel modules.
In the past it was not a problem because they are loaded as soon as
a device is added using the CLI.
Now we need some checks before doing this and they fail if this modules
are not loaded.

Loading modules while starting multipath is the standard behaviour in
more recent versions of multipath.
We just ensure this is always true.

Signed-off-by: Germano Percossi <germano.percossi@citrix.com>
Reviewed-by: Keith Petley <keith.petley@citrix.com>
Merge changes for CP-6337

Signed-off-by: Germano Percossi <germano.percossi@citrix.com>

GitHub: closes #54 on xapi-project/sm