webadmin: Edit data center dialog chooses shared type as default

When editing a data center, the type combo box was always set to shared
regardless of the actual data center type

Change-Id: Iaaaf55768a72bc6f3f1349077ee9d54f41aa4995
Bug-Url: https://bugzilla.redhat.com/1057155
Signed-off-by: Tal Nisan <tnisan@redhat.com>