webadmin: VnicProfilesEditor to inherit AddRemoveRowWidget

This to promote a uniform look between these similar widgets, as well
as code reuse.

Change-Id: If66c23bddada57fbfd95292dc2cc1f6c8d9df19e
Bug-Url: https://bugzilla.redhat.com/1025288
Signed-off-by: Lior Vernia <lvernia@redhat.com>