with a custom patch needed by edx-platform.
Upgrade django-filter as well to v1.0.4
Import DjangoFilterBackend from the correct module - django_filter.
Add django-filter to INSTALLED_APPS.

EDUCATOR-341

EDUCATOR-11

This reverts commit f97f0525, reversing
changes made to 800bcd8e.

LEARNER-76

TNL-6815

This specifically enables/disables the underlying comment service client
used to make calls to the service.  When disabled, this client will now
throw an exception which can be propagated upwards so that callers can
make the right decision about how to notify users of the error, or
handle retry, etc etc.

- Default of "desc" is all that is in use, and remains as-is.
- Discussion API keeps order_direction param, to minimize changes,
but it only accepts "desc".
- Discussion webapp simply no longer sends in the sort order.

- Default to with_responses=False, except when required.
- Clean up search call unused params.

We're often grabbing the metadata of a specific thread to then be able
to perform other operations, but we never need the actual responses or
comments of a thread unless we're displaying it in the normal forum
view.

This change sets a default of with_responses=False, which instructs the
comment service to not send back the responses/comments for the given
thread.  We only ask for responses in the case of rendering a single
thread or inline discussion.

* Renames discussion_module to discussion_xblock
* Moves common/lib/xmodule/xmodule_discussion to openedx/core/lib/xblock_builtin/xblock_discussion

More accurately, this creates a 4th shard because the
last shard is always the default.

More accurately, this creates a 4th shard because the
last shard is always the default.

This will leverage the nose attrib plugin to allow us
to break tests apart on our build system to run
in parallel on separate nodes.