-django-babel-underscore custom version to support django>=2.2

Upgrade ORA to 2.6.12 | When fetching file URLs from keys stored in Submission records, don't break just because we encountered one missing file; there might be more, existing files after it.

* Removing deprecated rest_framework_oauth library

* removing dependecy of django-rest-framework-oauth

* removing oauth_provider from cms

This reverts commit 1f32bc63.

-Updated middleware setting to use use middleware insted of
middleware_classes
-github install of django-method-override fork to support
new style middleware in django1.11

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

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

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

Wiki version bump.

Updating wiki.

There was a serialization issue with one of the studio JS assets that
is rendered as a part of the edit view.

- Undo the previous change.
- Pull in the version of codejail with the fix for the issue.