Review request update payload rendering now uses a BytesIO instead of

a StringIO to build any payloads, fixing issues with the payload

building caused by type mismatches. Some entry ordering discrepencies

have also been sorted out (no pun intended).
A few queries making use of Many-to-Many "through" tables have been

reworked to be compatible on both Django 1.6 and 1.11.
The raw diff download view also has a fix for a type mismatch in the

filename.

Unit tests pass on Python 2.7/Django 1.6 and Python 3.7/Django 1.11

(with other in-progress changes).