Rename order in CreditRequirement (2/3)

This stage does the following:

- Includes a data migration to copy the values from old to new field.
- Changes business logic to switch to using new field.
- Deletes all code references of the old field.

Upgrade DRF to 3.9.4.

Static files s3

Use ==/!= to compare str, bytes, and int literals

Undefined name: import datetime for line 30

Identity is not the same thing as equality in Python so use ==/!= to compare str, bytes, and int literals. In Python >= 3.8, these instances will raise SyntaxWarnings so it is best to fix them now. https://docs.python.org/3.8/whatsnew/3.8.html#porting-to-python-3-8

Without this change, line 30 will raise NameError at runtime.

ARCH-1253: remove shim_student_view from LoginSession.post - Part 3

Remove unused code

* Added pytest-json-report plugin
	- modifying app-opts in setup.cfg
	- adding hook to all conftest.py files in repo
	- setting report to be saved to test_root/log/warnings.json
	- Writing custom logic to save json report to avoid overwrite if pytest called twice
This was created to allow us to easily parse through test warnings in jenkins

Rename start in schedule 3/5

[REV-1061] Set discount on order based on discount that was on basket

Fixing typo

Fix test that assumes 2020 is in the future.

ORA update

Added on_delete parameter to models

Query optimizations

In Django template rendering, context processors only run once.
But when we do template rendering through edxmako (which we do for
each and every web fragment/XBlock), we can end up having hundreds
of invocations of templates and run context processors for each
separately. This removes that work.

This adds request caching to the following places:
* course expiration wrapper (displayed in Units)
* offer banner generation (displayed in Units)
* get_enrollment
* user_by_anonymous_id
* youtube_disabled_for_course

On a sample course with edx-val enabled, this reduced the queries
for a large sequence from 450 to 155.

In the script used to create the bok-choy database cache files, we've been passing in the parameters to omit timestamps that change for every run in some of the mysqldump commands but not all of them. Use them consistently so we can stop creating new redundant automated bok-choy DB cache PRs on almost every merge to edx-platform.

Safer CourseOverview.org filed matching

Lower the pylint threshold.

We fixed various deprecation warnings as part of BOM-1024

Fix all E303 pep8 errors.