webadmin: Hide panels related to Host Network QoS

Due to missing capabilities on the VDSM side, this patch hides the GUI
elements related to the Host Network QoS feature, effectively making
this a "dormant" feature. It does this simply by rendering containing
panels invisible for the moment, and should be easily-revertible when
the functionality is implemented.

Change-Id: Ibd7eb87542dc460ad09615fb850cc0354375d3e3
Bug-Url: https://bugzilla.redhat.com/1043230
Signed-off-by: Lior Vernia <lvernia@redhat.com>