Hidden bonds[2/2]: Refactored and updated nics implementation.

nics implementation now allows to hide bonds marked as hidden
in the config file.

Change-Id: Ieab80a3ca6b243ade75e490b7004bebe96248140
Signed-off-by: Giuseppe Vallarelli <gvallare@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/16239
Reviewed-by: Antoni Segura Puimedon <asegurap@redhat.com>
Reviewed-by: Petr Šebek <psebek@redhat.com>
Tested-by: Petr Šebek <psebek@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>