core: block virtio-scsi for unsupported OSes

Block VirtIO-SCSI for unsupported operation systems:
* Added isOsTypeSupportedForVirtioScsi method to VmHandler.
* Added an appropriate VdcBllMessage.
* Modified AddVmCommand and UpdateVmCommand accordingly.
* Updated tests.

Change-Id: Id9907d35b53c0447662bc638146c4c61ac5cce8a
Bug-Url: https://bugzilla.redhat.com/1038613
Signed-off-by: Daniel Erez <derez@redhat.com>