[fix] usable waffle admin

[aaxelb]

Purpose

make it possible to edit waffle flags thru the osf admin (/admin/waffle/flag/)

Changes

• upgrade waffle (by only one version -- will be upgraded further with python-upgrade) to allow disabling default model admins
• disable default waffle admins, instead register in osf/admin.py
• customize Flag admin: add 'groups' to raw_id_fields

QA Notes

Please make verification statements inspired by your code and what your code touches.

• Verify can view flags in the osf admin at /admin/waffle/flag/, can click on a flag to view details, and can save changes to flag config

What are the areas of risk?

Any concerns/considerations/questions that development raised?

Documentation

Side Effects

Ticket