JIRA:EDUCATOR-4242

The pinned version is the one tagged with a release that is also on
PyPI.

https://github.com/jazzband/django-pipeline/tree/1.5.3

Use PyPI instead since that will be faster.

This has the effect of preventing Open edX installations from having
details which should be in configuration (because they're
edx.org-specific) end up in their applications.

We used these when we were hooked up to gemnasium but
we haven't been working with that for a little while.

We intend for subsequent versions to be reviewed manually before
finding their way into edx-platform proper; this prevents subsequent
releases from finding their way in without human intervention

revert pillow version

was causing issues with PT exam configuration dashboard launch

This reverts commit 544c7f7e.

This is necessary to allow new proctoring backends to mark proctored
attempts in error, often due to unuploaded files from the application
or issues with multiple sets of files attached to the same testing
session.

Fixes: https://openedx.atlassian.net/browse/INCR-16