ifcfg: remove and re-create bonds when they are not to be destroyed

In order to make sure that bonds that should be left undestroyed,
but do not have users, are set with the default options and devoid
of any previous configuration, we delete the bond and its ifcfg
file and create new ones.

Bug-Url: https://bugzilla.redhat.com/1097674
Change-Id: If897e1ad96737916a6e440664295694790e2226a
Signed-off-by: Antoni S. Puimedon <asegurap@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/28062
Reviewed-by: Dan Kenigsberg <danken@redhat.com>