Add support for project-defined custom evolutions.
Review Request #10560 — Created May 21, 2019 and submitted
This introduces a new Django setting (
CUSTOM_EVOLUTIONS) for mapping
app names to custom evolutions modules, allowing a project to apply
mutations to apps that don't otherwise support evolutions. This allows
for situations like converting an app to use migrations when that app
was previously managed by Django Evolution but didn't itself use
Unit tests pass on Django 1.6 and 1.11.