Fix pcap2py to support negative timestamp, now work with radiolog.pcap from COOJA
Fix pcap2py to support negative timestamp, now work with radiolog.pcap from COOJA

bluerover/6lbr,bluerover/6lbr,bluerover/6lbr,bluerover/6lbr,bluerover/6lbr,bluerover/6lbr,bluerover/6lbr