This brings Python 3.x and Django 1.11 support to our webhook code.

There were a few key areas that required some rethinking in order for

modern support:


Python 2 has a long type, but Python 3 does not, so we just

   needed to alias long to int for testing purposes.


Python 3.x's JSON support doesn't handle sorting of non-string keys.

   They recommend avoiding non-string keys entirely, but it only breaks

   when sorting. However, our XML and custom payloads support them. We

   now normalize keys to strings if we know we're going to run the

   data through a JSON encoder.


We were outputting byte strings for JSON and form-data payloads,

   but Unicode strings for XML. We're now consistent in the format

   returned across all types.


Django 1.6 and 1.11 have different setup requirements for manually

   parsing templates and getting results. This has to be solved with a

   version check, and using different logic for each version of Django.


Django 1.11 tries to be helpful when encountering an invalid block

   tag, making recommendations about loading libraries. We don't want

   this at all, since users don't have this option with our webhook

   templates, so we now override this error message to be less helpful.

Unit tests pass for Python 2.7 with Django 1.6 and 3.5-3.7 with

Django 1.11 (with other in-progress changes).