add ability to see which pcap file a stream is from and download pcap

[zupd]

One thing we have noticed while using Caronte is that it's hard to find out
which pcap file a specific stream is from. If you want to manually look at packets/streams
before and after the stream you have found in Caronte, we had to basically download
all pcaps and just open all of them to find the correct stream.

1. Would be awesome if there was some info about which pcap file a stream/packet is from.
2. Possibility to download the entire pcap the specific stream/packet is from.