Can't send binary data to httpbin.org

[ib-lundgren]

@Lukasa do you know if it is possible to send binary data to httpbin nowdays?

It used to be possible to /post but it now returns 500, which breaks test_core.py#96. If it is no longer supported in any endpoint we should either find another service or try and mock it out.

[Lukasa]

Interesting.

I've not tried it recently and I don't think it's common, but I'd have expected it to work. If it doesn't I think that's a bug.

[ib-lundgren]

Opened https://github.com/kennethreitz/httpbin/issues/141, will see if anyone there knows.