Stabilize textbook tests

Update translations (autogenerated message)

Cdodge/restricted oauth2 applications

Allows ChoiceResponse problems to set correctness with python variables

determine choice correctness, as MultipleChoiceResponse problems already do.

Adds a unit test for this change, and for the existing MultipleChoiceResponse
computed correctness capability.

Update persistent grades asynchronously

ORA version update

Move dark_lang and lang_pref apps to openedx/core

Merge hotfix back to master.

Pull hotfix in to release branch.

For better user-facing performance, the SCORE_CHANGED signal is now handled by
enqueueing an async task to update the relevant stored grade, rather than
making the request wait until that operation finishes.

TNL-5738

Revert "Cdodge/restricted oauth2 applications"

Fix for spurious 'cb() never called' errors.

Cdodge/restricted oauth2 applications

Also, help with an echo.

Fix flaky bokchoy test: test_automatic_cohort_help, test_manual_cohort_help

add location to attributes exported to neo4j

Move more urls.py

add child context check to unit page title TNL-5746

Remove config_models & use external config_models repo instead.

Some Jenkins builds are erroring when attempting to set up the
npm environment with the error:

`npm ERR! cb() never called!`

Although it could point to a couple of different things, it is more classically
a sign of a dirty npm environment cache. Cleaning the cache at the start
of any given Jenkins job (which are sourced through this file) should
alleviate the problem.

TNL-5709

Fixing flaky test_studio_help_links

Return with an error code from the coverage reporting bash script

Disable migrations by default in python unit tests

Merge release -> master for release-2016-10-12

Rendering model states when running migrate in Django 1.8 consumes
on the order of 4x-6x more memory than <1.8.

References:
* https://code.djangoproject.com/ticket/24745
* https://code.djangoproject.com/ticket/24743

This is causing failures in Jenkins as the workers run out of memory
and either processes cannot fork or the Out Of Memory Killer
kills a process that is running tests.

Disabling migrations until we do either or both of these:
* Upgrade to Django 1.9 and turn them back on. See EV-92 "Discovery: Upgrade edx-platform to Django 1.9"
* Address TE-1310 "Unit tests should be able to run without migrations"

Sstudent/hack instructor task

Grading Policy endpoint in Grades API