webadmin: qos parent sub tab

Adding a QoS container sub tab to hold all qos entity
subtabs (storage and network), without changing the model layer.

Change-Id: I6d5e2de2d979bdaab498922acd6a580bc89dc19a
Bug-Url: https://bugzilla.redhat.com/1085049
Signed-off-by: Gilad Chaplik <gchaplik@redhat.com>