-Adressed all comments

-Updated method "course_key_from_string_or_404" to raise message too.
-Wrote tests for "course_key_from_string_or_404" when exception message is given.
-Modified existing methods to use "ddt.data".
-Used Splunk logs to find exectly where we were getting "Invalid Key Error"
-Updated Views where we were getting "Invalid Key Error" in splunk logs.
-Wrote tests for those View End points where we were getting "Invalid Key Error"

TNL-4324: Add check for strings that should be wrapped with HTML()

API request page improvements.

rtl support static pages

Fix encoding of Django-called Mako files to be safe

ECOM-4024

remove unnecessary parentheses

change css properties for mixins bi-aap in login/register page

change css properties for mixins bi-app in about course page

change css properties for mixins bi-app in the dashboard

change css properties for mixins bi-app in help template

change css properties for mixins bi-app in the home page

change css properties for mixins bi-app in jobs, press and media pages

remove the extra spaces

- Make mako-wrap-html fire when '<' found anywhere in unwrapped string
- Fix typo
- Fix quality errors
- Fix defect found when Python string broken over lines

Also include the following:
- new rule for strings that should be wrapped with HTML()
- allow expressions to use "| n, unicode"
- refactor string parsing into separate class
- switch end_index to be the index following the expression

Add a11y test for the course home page.

Allow the "Default Group" to be renamed (automatic cohorting)

TNL-4324: Enhance linter for HTML() and Text()

ECOM-3198 Add banner image to the program listing program cards

The old code set the output-encoding to None, which means, I want
Unicode strings as output.  This made Mako pass markupsafe objects to
"unicode()", which applied all the escaping.  Then the result would be
given to Django, would would html-escape it again, resulting in
over-escaping.

By setting the output-encoding to utf8, we use filters.encode.utf8
instead, which is aware of Markupsafe, which avoids the over-escaping.

- Add capability to run linter on file or directory
- Add rule for HTML() requiring Text()
- Add rule for HTML() and Text() being closed before format()
- Add rule for Text() unnecessary without HTML()
- Enhance expression parsing
- Add real arg parser for script
- Clean up unit tests

Introduce Pattern Library test pages (take two)

Lower padding on header for 320 breakpoint.

FEDX-88. Marking bok-choy test as flaky.

FEDX-93

These are developer only pages, so can not be seen in production
environment. On devstack, you can access these pages in LMS and
Studio at:

    /template/ux/reference/pattern-library-test.html

This is the second attempt to enable the Pattern Library. The
first attempt broke Django Templates and didn't work correctly
with right-to-left styling.

TNL-4355

Revert "Introduce Pattern Library test pages"

Add configurable name for verified track cohort.

Course Updates date validation

Adding i18n info for developers

Decreased the flakiness of upload_tar function

This reverts commit 845e3708.

Remove unused imports

Submission History safe by default

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.