webadmin: Fix gluster cluster selection in host dialog

After selecting a gluster cluster from the System Tree,
when try to create a new host, the host dialog doesn't
select the correct cluster and DC. This fixed now.

Change-Id: I7472e5c50687057860288c8f1ba652fff9fb3cb2
Bug-Url: https://bugzilla.redhat.com/851084
Signed-off-by: Kanagaraj M <kmayilsa@redhat.com>