webadmin: show disks allocation panel on edit VM

Disks allocation panel should be available
on edit VM dialog in case VirtIO_SCSI is
applicable.

Change-Id: If433ac77686407d53a79f68a8699b58316df51c8
Related-To: https://bugzilla.redhat.com/1035289
Signed-off-by: Daniel Erez <derez@redhat.com>