Refactoring: Use format with named variables

Adding a reviews page to the course and updating the reviews module on the course about page. Removed the existing coursetalk implementation and put it in a fragment, removed the tests as well. Added configuration settings to specify the reviews template as well as the reviews provider. This is all protected by a waffle flag.

LEARNER-1341

- Keeps platform set default of "Audit" to be backwards compatible and not break stuff
- get COURSE_MODE_DEFAULTS from config if set

move tasks into tasks.py

add more logging

Defaults to SUPPORT_SITE_LINK intentionally.
Also fixed surrounding quality tests, and overall
quality improvements.

https://openedx.atlassian.net/browse/EDUCATOR-393

This reverts commit f97f0525, reversing
changes made to 800bcd8e.

This also serves as a slight refactor of ENT-392.

https://openedx.atlassian.net/browse/EDUCATOR-389

EDUCATOR-274

This makes it possible to refer to multiple book from a single app.

This also means that Open edX branches will be able to pass bok-choy
tests (at least if the books have already been built.)

This reverts commit 65f13dde.

This reverts commit 88dd85ca, reversing
changes made to bf8aef33.

TNL-6674

Fixes migration error thrown by edxapp-migrate-cms

- Creates a new app under cms
- Sends emails asynchronously on completion of any top-level job
- Moves old user task related cms tests to cms_user_tasks