webadmin: Force uniform capitalization of "vNIC"

There were several variations of capitalization, made them all the
same.

Change-Id: I4c8dd1c43f7d3e9fe38fa3c1b1b2592488e0090b
Bug-Url: https://bugzilla.redhat.com/970900
Signed-off-by: Lior Vernia <lvernia@redhat.com>