[CARD Technical Issue] Dropping FMIPv6 piggybacking

Section 4.5 describes a negotiation between the MN and AR to determine
whether CARD is piggybacked on FMIPv6. This negotation seems complex and
unnecessary. For simplicity, I think we should do one or the other. Though I
favor piggybacking because it simplifies the entire handover across both
protocols, requiring the MN to negotiate whether to use FMIPv6 makes the
handover more complex. Since the DT and WG don't seem to agree, I believe we
should drop FMIPv6 piggy backing.

            jak