Updated deprecated manage.py code, added authorization tests to tox.
Enabled customuser tests in tox, fixed customuser tests, changed run_all_tests.sh to work with all versions of Django.
Removed data shared on Field objects, changed code to reuse related resources.
Removed ApiField.value, which is unused and undocumented. It seems to be leftover from when field objects could store values and be serialized.
Merge branch 'test-enhancements' into all-the-branches
Merge branch 'data-leakage-fix' into all-the-branches