webadmin: disk dialog - VirtIO-SCSI availability hint

Add/Edit disk dialog:
When VirtIO-SCSI is supported by the cluster but disabled
for the VM, display an info icon next to Interface dialog
(with hinting that VirtIO-SCSI can be enabled from
Resource Allocation tab on VM dialog).

Change-Id: I9a2bd43de2adb0e85d3848042622fdce69e07ac0
Signed-off-by: Daniel Erez <derez@redhat.com>