Explore and implement rate limiting

[sburnett]

We should figure out if we need to limit the bitrate of the uploader, and implement if so.

Rate limiting would be useful after long periods of uplink unavailability, when lots of files need to be uploaded.

[ggmartins]

OK, how about using iptables to mark the process packets with pid-owner and have the TC for rate limiting
http://unix.stackexchange.com/questions/34116/how-can-i-limit-the-bandwidth-used-by-a-process