Merge release back into master

Make Robust Grades Robust Again

Update coverage version to 4.2

Don't delete question p-tag if children.

Reduce sql queries with persisted grades

As part of the Robust Grades rollout, we expect to see some DatabaseErrors in
various methods that write to the database. Since the success of this write
operation is not needed for the end-user, we just log and swallow the error.

In the future, we'll also enqueue an async task to finish the write operation
that failed.

TNL-5458
TNL-5493

TNL-5510

Change edx-django-release-util version.

Update opaque-keys and ccx-keys versions.

Merging hotfix/2016-09-13 release into master

Fix the duplicate oauth_body_hash in the outcomes request

Wrap the discussion header in a <nav aria-label="Forums">

TNL-5193

TNL-5240: Cache comment thread.

AC-581 using UXPL values for course types on dashboard

Merge release into master

The "oauth_body_hash" appeared twice in the auth header in the request
when posting grade back to tool consumer. However, the signature sent
from edX is calculated based on only one oauth_body_hash.
On the tool consumer side, the signature is calculated based on the auth
header and will use the duplicated fields. So the signatures will not match.
And request will fail the signature validation.

The bug was introduced in this commit:
https://github.com/edx/edx-platform/commit/03cee389e0869263f5f9977098770495b5216733
on July 12th by updating the oauthlib.

Because 0.7.2(original version) doesn't have oauth_body_hash support, so a custom
OAuth1 client was implemented to add oauth_body_hash to the headers:
https://github.com/edx/edx-platform/blob/f5d0f3ff55d264ed4b68a24808b255aef5d8dad2/lms/djangoapps/lti_provider/outcomes.py#L24.
However, the new oauthlib 1.0.3 has support for oauth_body_hash
(https://github.com/idan/oauthlib/commit/51675237c410b413a11091926436420493c52866#diff-c2a1e5f1ddfe8e48ff62b59eb952644eR180).
So after updating library, oauth_body_hash is added twice.

This fixes the bug by removing the custom client and use the oauthlib
default client to generate the auth header.

Cache Enrollment state for (user, course) in request cache

patch/2016-09-12

Fix RTL issues with discussion sass

logging

Enable Persistent Grades in unit tests

TNL-4709

Fix extremely minor box corner issue in Discussions

Catalog-based MicroMasters need to be displayed in the LMS. However, the LMS currently retrieves all program data from the soon-to-be-retired programs service. Consuming program data exclusively from the catalog service is out of the question right now; it's too complex to confidently pull off in a week. This is a functional middle ground introduced by ECOM-5460. Cleaning up this debt is tracked by ECOM-4418.

Enable discussion forums on CCX courses.

Discussion is restricted to the CCX course (there is no sharing of
discussions with the parent course or other CCX instances).