Frontera Request/Response decoding/encoding doesnt work between python 2/3 versions

[whalebot-helmsman]

There is an error when you encode Request or Response in one python (e.g. python2) and decode it in another(e.g. python3).

How to reproduce? All information in one gist

I split tests/test_codecs.py in three parts - common.py(request shared between read and write for comparison), read.py(requests read from msgpack and compare with requests from common) and write.py(write to msgpack requests from common)

if I write/read in same python, all is work. But if switch between versions error appears. Look at attached to gist write-2-read-3.txt and write-3-read2.txt files.

[sibiryakov]

Thank you for the report. Could track down where the problem is, and submit a PR?