webadmin: Add full host network QoS dialogs

Implemented the complete host network QoS dialogs (add/edit/remove),
to be used from the DC/QoS subtab and (some also from) add/edit
network dialog.

Change-Id: I212708b25777f5d11245a610d4d767f634cb9f88
Signed-off-by: Lior Vernia <lvernia@redhat.com>