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

* Constraining edx-rest-api-client

* Decreased pin on edx-rest-api-client from <3.0.0 to <2.0.0

Unpin several more outdated dependencies whose changelogs don't contain any significant backwards incompatible changes. Also add "moto" to the list of packages to uninstall from existing environments, since it requires a jsondiff version that clashes with the one we now use (triggering a harmless but distracting warning on dependency updates).

We can potentially stop using path.py/path altogether by switching to pathlib in the Python 3 standard library, but that merits a separate PR of its own.

Also, note that I'm not actually unpinning freezegun; different PRs restricted it in both constraints.txt and test.in, I'm just removing the latter redundant constraint.

Added the link to latest master commit of GitHub for Django 2.2 support.

Removing the moto.

django-appconf bump version using commit hash for django2.2

This is step 3 of DE-1824.

Also update:
* six 1.13.0 => 1.14.0
* edx-django-utils 2.0.2 => 2.0.3
* skip test that checks all model changes have migrations.  (We defer
  this to step 4.)

Removed the version constraint for django-mysql
Also pinned the freezegun version to 0.3.12 as the latest version is causing failures.

Bump django-filter.
Rename the name to field-name.

Wiki version bump.

bumping enterprise version to 2.0.45

Updating wiki.

made changes to test with previous version of django-waffle

updated the query count to test

testing with version 0.13

testing with version 0.14

testing with version 0.15

added version 0.14

updated the django-waffle version to use 0.18

updated the django-waffle version to use 0.16

updated the query counts to pass tests

ran make upgrade

updated the django-waffle to support django 2.2

made changes to test with previous version of django-waffle

updated the query count to test

testing with version 0.13

testing with version 0.14

testing with version 0.15

added version 0.14

updated the django-waffle version to use 0.18

updated the django-waffle version to use 0.16

updated the query counts to pass tests

removed the pdb statements

ran make upgrade