Add functional code that loads a pcap file and constructs the IP->hostname map/dictio...

Add functional code that loads a pcap file and constructs the IP->hostname map/dictionary. Note that the map is actually of type Map<String, List<String>> as the trace contains cases where ONE IP maps to MULTIPLE hostnames. Bug in current implementation: the map should be changed to Map<String, Set<String>> to prevent the same hostname from showing up in the list multiple times (occurs when a set of DNS queries return the same IP).