Updating the django-rate-limit requirement.
updated the django-ratelimit to use unreleased version that supports Django 2.2

This will remove imports from __future__ that are no longer needed.

https://docs.python.org/3.5/library/2to3.html#2to3fixer-future

Implementation details:
* Anonymous users are assigned a unique ID (like 
  `anon42c08f9996194e2a9339`) which gets stored in the django session.
  `block.scope_ids.user_id` and `block.runtime.anonymous_student_id`
  will both return this value.
* User state for anonymous users is stored in the django cache and
  automatically expires as the cache gets pruned. Because user state is
  stored, anonymous users can use interactive blocks like capa problems.
* There is no mechanism for upgrading to a registered account and
  keeping user state since the user state store for anonymous users
  (EphemeralKeyValueStore) is completely different than the one for
  registered users (DjangoKeyValueStore/"CSM"), and has no "list all
  keys" functionality.
* "User State Summary" field values are shared among [recently active]
  anonymous users but are not shared with registered users.
* Anonymous users can only access the `public_view` of XBlocks, not the
  regular `student_view`.

This completes the work started in https://github.com/edx/edx-platform/pull/19453
to use the LMS login and registration for Studio, rather than Studio
providing its own implementation.

LMS login/registration are being used for the following reasons:
1. LMS logistration properly handles all SSO integrations.
2. A single logistration is simpler to maintain and understand.
3. Allows Studio to work more like all other IDAs that use LMS
logistration.

The original switch to use LMS logistration for Studio also added the
toggle `DISABLE_STUDIO_SSO_OVER_LMS` to provide the community some
additional time for switching. This commit removes this toggle, which
at this point means all deployments will use the LMS logistration.

This change requires sharing cookies across LMS and Studio. Should that
prove to be a problem for certain Open edX instances, there are
discussions of possible alternative solutions.
See https://github.com/edx/edx-platform/pull/19845#issuecomment-559154256

Detailed changes:
* Fix some Studio links that still went to old Studio signin and signup.
* Remove DISABLE_STUDIO_SSO_OVER_LMS feature toggle.
* Remove old studio signin and signup pages and templates.
* Fix url name "login", which had different meanings for Studio and LMS.
* Use the following settings: LOGIN_URL, FRONTEND_LOGIN_URL,
FRONTEND_LOGOUT_URL, and FRONTEND_REGISTER_URL.
* Redirect /signin and /signup to the LMS logistration.
* Add custom metric `uses_pattern_library`.
* Add custom metric `student_activate_account`.
* Add Django Settings to allow /signin, /signup, and /login_post to be
disabled once ready.

This work also relates to ARCH-218 and DEPR-6.

ARCH-1253

* Always run CSMHE migrations for every application in all contexts

This commit introduces the changes needed for XBlocks in Blockstore to save
their user state into CSM. Before this commit, all student state for Blockstore
blocks was ephemeral (in-process dict store).

Notes:

* The main risk factor of this PR is that it adds non-course keys to the
  course_id field in CSM. If any code (like analytics?) reads course keys
  directly out of CSM and doesn't have graceful handling for key types it
  doesn't recognize, it could cause an issue. With the included changes to
  opaque-keys, calling CourseKey.from_string(...) on these values will raise
  InvalidKeyError since they're not CourseKeys. (But calling
  LearningContextKey.from_string(...) will work for both course and library
  keys.)
* This commit introduces a slight regression for the Studio view of XBlocks in
  Blockstore content libraries: their state is now lost from request to request.
  I have a follow up PR to give them a proper studio-appropriate state store,
  but I want to review it separately so it doesn't hold up this PR and we can
  test this PR on its own.

API docs are now always available, no more toggle to enable them.

The proctoring app assumes that this setting exists and so we get an
attribute error at runtime if it doesn't.  In python 2 this was not an
issue but because of the change in how exceptions are handle for getting
attributes, it's a problem in python 3.

The correct thing to do would be to fix this in the proctoring app so
that it checks for the existence of its value before using it but that's
a longer cycle to make/deploy that change so doing this as a stopgap to
get past it.

https://github.com/edx/edx-platform/pull/20645

This introduces:
* A new XBlock runtime that can read and write XBlocks that are persisted using
  Blockstore instead of Modulestore. The new runtime is currently isolated so
  that it can be tested without risk to the current courseware/runtime.
* Content Libraries v2, which store XBlocks in Blockstore not modulestore
* An API Client for Blockstore
* "Learning Context" plugin API. A learning context is a more abstract concept
  than a course; it's a collection of XBlocks that serves some learning purpose.

Added check to only apply the changes for
edx.org help center pages.

Use `ascii_letters` instead which is a reasonable alternative for our
usecases.

* reword INCR-483: Make compatible with Python 3.x without breaking Python 2.7 support

pick INCR-483: Re-run isort for lms/envs/test.py

INCR-483: change import order

INCR-483: PyLint fixes

* INCR-483: Fixes useless suppression

* INCR-483: Remove unused get_swagger_view

Dashboard is set to load 250 courses instead of
all the courses. A flag is also added to change
the number the courses to load.

PROD-204

ENT-1887 | Adding logic for new business marketing footer url construction, while maintaining backwards compatibility

Fixing quality test

Testsing out a default value for the sake of jenkins tests. will revert

Fix footer test from being flaky

Moving an import statement

ran isort. adding a test. fixing 1 quality issue

Quality cleanups

Attempting more quality fixes

adding back in config variable name for default value

Adding ENTERPRISE_MARKETING_FOOTER_QUERY_PARAMS to common settings

Changing marketing_url logic to only concatenate enterprise url to root if the enterprise url is relative (starts with a /)

quality fixes

Adding logic that adds roles to jwt

Quality fixes

Removing the Deprecated the 'external_auth' package in favor of 'third_party_auth' which is the current recommendation.

This is a feature that has been deprecated and can be safely removed.

DEPR-7

The JWT_COOKIES_FLAG was a temporary flag used for rollout of the new
JWT cookies. These are live in Production, so we are removing the flag.

Without this flag, we set JWT cookies during login. However, this
requires an oAuth Client that isn't always available during unit tests.
We introduced a feature flag that is only used for unit tests to
disable setting the JWT cookies. The code explains a bit more why this
solution was selected over adding the oauth client to the database.

ARCH-247

relied on the old configuration values and old way of validating
passwords. Also improved registration page by always showing error
messages rather than hiding them on leaving the field.