This adds ability to refresh the list of uploaded videos without refreshing the whole page.

Added a refresh button that when clicked:
- fetches a fresh list of uploaded files from the server
- updates `PreviousVideoUploadListView`
- removes the successfully completed uploads from `ActiveVideoUploadListView`
- retains the ongoing or failed uploads in `ActiveVideoUploadListView` so that they can be monitored/retried

The view can also be refreshed without user action, but I felt it may be less surprising to have a button instead.

MA-333 update: auto-refresh list, fix test failure

Changes:
1. Refresh of file list triggered by upload completion. Refresh button retained and label changed to "Refresh List".
2. Added `aria-live="polite"` to `.active-video-upload-list` and `.assets-table`.
3. Removed unused parameter `evt`.
4. Added self to the `AUTHORS` file.

MA-333 update: added tests

MA-333 update: removed refresh button

MA-333 update: address review comments of @mushtaqak

MA-333 update: simplify nested `_each`

MA-333 update: rename viewRefresh to isViewRefresh

MA-333 update: doc string for `clearSuccesful`

MA-333 update: fix accessibility

MA-333 update: update only successfully uploaded videos

MA-333 update: use window.SR feature to notify screen readers that video upload was successful (@pomegranited)

Previously, retry() was never called, so the task was never retried despite
defining several retry-related variables.

TNL-5083

It should help catch unicode encoding problems earlier.

This also updates python-saml dependency to a version that includes a
patch for unicode strings.

The `commit` argument had already been removed from code [1][2][3],
prompted by the django18 upgrade.

[1] https://github.com/edx/edx-platform/pull/10927
[2] 07f015bb
[3] a4006c86

FEDX-176

Replaced lettuce tests with bokchoy tests for the course updates page and improved flaky test issues.
TNL-5051

Removes most remaining hardcoded references to XSeries from the LMS. Part of ECOM-4638.

ECOM-4890

Basic architecture of Maintenance App - SUST-19, SUST-42. Implement Force Publish Course view. SUST-46

Revert "Basic architecture of Maintenance App - SUST-19, SUST-42. Implement Force Publish Course view. SUST-46"

This reverts commit 27646b7e.

2. Add site configuration overrides to theming/helpers.py
3. Move microsite.get_value from theming/helpers to site_configuration/helpers
4. Move microsite_configuration.microsite.get_value usages to site_configuration.helpers.values

Basic architecture of Maintenance App - SUST-19, SUST-42. Implement Force Publish Course view. SUST-46

TNL-4670

TNL-4906 Subsections now use radio buttons, to allow for "hide after due" as a
visibility option. Also, all tabs have been consolidated to "Basic" and
"Advanced", and visibility options have moved there.

Documentation links are updated to assist course authors with the new
visibility options. Tests have also been updated, and the changes suggested
in TNL-4951 are included.