webadmin: Fixed description in edit affinity group

In the "Edit" popup of the "Affinity Group" subtab for the VM
The description field wasn't retrieved(It was left empty even after
being set). This error was fixed and now description field that was set
will be shown in the edit popup.

Change-Id: Ib0e88bc052844a5cfca30b0f1c53bf1b118c2ae3
Bug-Url: https://bugzilla.redhat.com/1142233
Signed-off-by: Tomer Saban <tsaban@redhat.com>