show Save and Cancel button when admin change Instructor image asset path from Studio schedule and details page

fix the issue where images do not appear when set through asset linkin Studio scheduls and details page

TNL-4115. Previously, course updates (which are intended to be posted with
dates, for sorting in the LMS) could be authored in studio with a valid
date, nothing, or a random string as the "date" for the update. As there
is no validation for this in studio, everything succeeded with no warning.

However, the LMS has problems parsing some of these values, and barfs when
loaded by learners.

The fix does two big things:
- gracefully handles invalid dates in LMS. These updates are now treated as
having a date of today, for sorting purposes.
- turns on validation in studio. Now, it is not only impossible to enter
invalid dates in studio, but notifications will draw the course author's
eye if any invalid updates were previously saved.

Test additions for this commit:

Adds:
- unit test for LMS parsing
- Jasmine test to confirm invalid dates cannot be set by the user
    -also adds event to setAndValidate instead of using a global object
- fix for lettuce test
    -It is no longer valid to enter the string "January 1, 2013" as this test
    had been doing. Keyed-in entries must use MM/DD/YY format.

Instructor-led is changed to instructor-paced. Adds a label to the
course outline page to show the course pacing.

ECOM-2794
ECOM-2800

Also adds improved styling for course pacing settings, and unit tests
around query counts for self-paced courses.

ECOM-2650

Currently unstyled.

ECOM-2462

ECOM-1648

ECOM-1591

Filter by Language:
Designation for course language(s) in Studio
allows for filtering of courses based on their language in the sidebar
Reuses active filter view UI/IA from find courses page on edx.org
view for clearing individual or all filters, as with edx.org filtering

The surplus ":" in the input selector causes jquery versions past 1.9 to throw an error.

Use native checkboxes for courseware license options
In Studio settings editor for video module, don't show license if feature-flagged off
Don't let Scope.contents fields leak to Studio editor
JS gettext() must all be on the same line for i18n
Add docstrings for bok-choy tests
Remove LicenseMixin from HTMLDescriptor
Responding to UX review feedback
Add aria-pressed attribute
Use https links instead of protocol-relative links for links to creativecommons.org
Remove license from course outline page in Studio

This allows course authors to choose between two difference licenses for their
course content: All Rights Reserved, or Creative Commons. In the backend, XBlocks
that wish to allow custom licenses need only inherit from LicenseMixin, which
adds a `license` field as a string.

License information is displayed in the Studio editor view, and just below the
rendered XBlock in the LMS. In addition, if the course block itself has a custom
license set, this license will display just below the main body of the page
on courseware pages.

This entire feature is gated behind the LICENSING feature flag.

* updating vendor files
* updating class syntax (to new FA-based classes) for all UI elements
* correcting broken tests

STUD-1506

http://bgrins.github.io/codemirror-accessible/)
LMS-1802

STUD-946
STUD-947

cleanup

Updates.

Testing changes.

Testing changes.

asset-index progress state cleanjup.

cleanup

Also change the file uploader to accept multiple file types.

Authors can upload an image (or choose an existing one) from the
settings page, using the in-context uploader from PDF
textbooks. Includes tests for backwards compatibility with XML courses
-- they used a magic filename (images/course_image.jpg) which is
mapped to a location in the Mongo contentstore.

Still needs some UX work, though the backend plumbing is there.