Record of work for prototype pcap parser

[stephen-soltesz]

The following PRs illustrate variations on a prototype pcap parser. More details are included in each PR.

• https://github.com/m-lab/etl/pull/1028
• https://github.com/m-lab/etl/pull/1032
• https://github.com/m-lab/etl/pull/1033
• https://github.com/m-lab/etl/pull/1034
• https://github.com/m-lab/etl/pull/1037

TODO:

• Summarize key take aways from these PRs.