CP-6271: Set default mode for XSM checks to use UUIDs

After this change the code at xapi_vm_migrate.ml:362 will
check if the VDI exists (by UUID) in the destination SR.
If it does, a mirror will not be performed as the VDI already exists.

The original behaviour can be used by setting the value to false in xapi.conf

Signed-off-by: Bob Ball <bob.ball@citrix.com>
CA-114333: Allow Linux HVM guests to use >4 devices.

Windows PV drivers don't check the guest device name, but the Linux kernel does
With devices > 4, Linux expects them to be in xvdN format, so this patch ensures
that all devices are treated as Linux devices

Signed-off-by: Bob Ball <bob.ball@citrix.com>

Conflicts:

	ocaml/xenops/device_number.ml
CA-99828 Add a new bond option: lacp-fallback-ab

lacp-fallback-ab allows lacp bond to fallback to active-backup
when there is no lacp partner.

Signed-off-by: Ravi Kondamuru <Ravi.Kondamuru@citrix.com>
Update datamodel.ml

Clarifying the event class documentation. from is better than next and correcting the return from "from" to include the token which was absent.
Merge pull request #1529 from rhb21/patch-1

Update datamodel.ml
Merge pull request #1525 from ravikondamuru/CA-99828

CA-99828 Add a new bond option: lacp-fallback-ab
Merge pull request #1498 from BobBall/cp-6271

CP-6271: Set default mode for XSM checks to use UUIDs
Merge pull request #1452 from BobBall/device_numbering

CA-114333: Allow Linux HVM guests to use >4 devices.