webadmin: Remove advanced parameters from vNIC dialog

Since the port mirroring checkbox moved to the vNIC profile dialog,
the advanced parameters section in the vNIC dialog only includes
plug/unplug at the moment, rendering it quite unnecessary. Also
rearranged some of the widget declarations so hitting tab will move
between them in a more logical order.

Change-Id: Idc9e865f9f8c2fe371d3a33703ea1a8172fea8aa
Bug-Url: https://bugzilla.redhat.com/1011999
Signed-off-by: Lior Vernia <lvernia@redhat.com>