Merge release into master

Patch/2016 04 05

Excluded admins, staff and coach of master course from max enrollment

Merge RC back into master.

Without this, when CCX runs 0003 it'll invoke course_overviews while
loading a course, but that table has a model change, and the migration
has not run yet.  This ensures the course_overviews migration happens
first.

Automatic cohorting of verified track learners

TNL-4336

TNL-4281.

Fix safe template change on dashboard

Prevents start date alone from being used to filter out categories in self-paced courses during construction of the category map. ECOM-4017.

Exposes an advanced setting in Studio allowing course teams to bypass the home tab when students arrive from the dashboard, sending them directly to course content. ECOM-3961.

It doesn't make sense to list these LMS block attributes in course-level advanced settings. Doing so is confusing to course teams.

ECOM-3673 Update the course end date description text to remove the reference to certificate when course enrollment is in audit mode

Fix discussion category map for self-paced courses

Request API access.

Prevents start date alone from being used to filter out categories in self-paced courses during construction of the category map. ECOM-4017.

ECOM-3940

MA-2257

Compile js strings when we make dummy strings.

Fix broken French i18n in CMS tests

Safe templating changes for CCX.

French ugettext method was being monkey-patched with a "XYZ " prefix in
all tests. This introduces a context manager to guarantee that the
function reverts to its original state after the unit test has ended
(successfuly or not).

Fix paver watch_assets

Upgrade Underscore.string

Update browser support link

paver uninstall_python_packages

Upgrade to Django 1.8.12

FEDX-117

Translate preferred languages in user account settings

Fix links to moved sections of the developer guide

TNL-4236 – Check for video transcripts before using it

The listed languages in the "preferred languages" input dropdown should
be translated in the user language.

- Update to latest version of watchdog.
- inotify doesn't work on nfs share in devstack. Use polling instead.
- Some editors (vim) do not trigger modify events in their default
  configuration. Rebuild assets on all filesystem changes, and debounce
  when changes happen too quickly.

Using edx-ccx-keys from PyPI