Uploader is so close to working under Python 3

[konklone]

I've been trying to get ~40GB of government reports into the Archive, as detailed in unitedstates/inspectors-general#63. It's a Python 3 project, so I've been running up against some hurdles.

1. Annoying, but not a dealbreaker, is that I can't use the [speedups] tag in my requirements.txt, because gevent is not compatible with Python 3. I see you're working on a refactor to use asyncio, which I 👍'd in Use trollius (asyncio) instead of gevent. #75 (comment) and would be very helpful.
2. A bigger problem is that the uploader and request object do some unicode encoding/decoding stuff that doesn't exist in Python 3 (because all strings are unicode strings) and is depending on __iter__ not being defined on str (in Python 3, it is).

I resoved 2. with a surgical but ugly hack, which you can see in this branch compare, and so now I'm working off of my fork for the time being.

To make the uploader work under Python 3 and still work under Python 2 will require a bit more work than my hack, but it should be possible.

[jjjake]

Uploads should now work in py3, see e34f625

[konklone]

Thank you!!