core: 2 SDs is now 2 Domains (#861134)

After copying a template disk, when the belongs to two domains, the
Disks tab showed 2 SDs under the Storage Domain(s) column. It now shows
2 Domains.

Change-Id: I8b256a5b92fbd2509b3860df1e17dbba0fd1ea3d
Bug-Url: https://bugzilla.redhat.com/861134
Signed-off-by: Vered Volansky <vvolansk@redhat.com>