obfsproxy rate limiting
As a temporary workaround to the hurdles of #3587 (moved), I implemented rate-limiting internal to obfsproxy; like it was discussed in Canada.
Basically, there is a new obfsproxy option '--throttle=' which sets the read/write rate/burst per second, to kilobytes.
It's not really flexible (no way to specify different values for read/write or rate/burst), but it serves as a basis for future work... maybe.