HTTP server: add landing page w/ some basic features

[wgreenberg]

17 implements an HTTP server with two routes: one for creating/downloading a pcap, and the other for downloading the qmdl file.

I think we should add a landing index.html page for the server that has a couple things:

• links for the above 2 routes, along w/ metadata on how large the qmdl file currently is, when it was created, etc
• basic system stats (free storage remaining, free memory remaining)
• some realtime (at the time of request) indicator of whether logs are successfully being recorded. maybe even streaming the daemon logs to the page?

[wgreenberg]

done!