Add Ability to Reference Raw Network Traffic

[ikiril01]

We should consider adding the ability to reference raw network traffic (likely as an Artifact-Object encoded PCAP file) recorded for a malware instance as part of a Malware Subject. I think this is very similar to how we plan on implementing the ability to reference static features of the binary - i.e., through a Raw_Network_Traffic field of type ObjectReferenceListType.