packet-netflow.c: Update "Information Elements" dissected based upon 08/13/2014 IANA IPFIX assignments document

Change-Id: Icfabdf5b77cdeef686620b75e649fc5bc270197a
Reviewed-on: https://code.wireshark.org/review/3996
Reviewed-by: Bill Meier <wmeier@newsguy.com>