add lock and unlock icons to subsections that require prereqs depending on whether the prereq has been met or not

Remove some obsolete and broken a11y markup that was causing
keyboard navigation in the main course outline to focus elements
that shouldn't be focused.

LEARNER-2893

In IE, when a user presses the bookmark/remove-bookmark button,
the focus was lost on that button because we set disabled=true
while we do the operation. Set the focus back when we are done.

LEARNER-2896

- Certificates management commands updates
- Moving reverse calls in tests into setUp from class definition
- Import shuffling
- Consolidating cryptograhpy version to 1.9

Add explicit 'lms.djangoapps' prefix to all commerce imports, as another
commerce Django app exists at openedx.core.djangoapps.commerce

Fix certificates visiblity to students on the profile page before the issue date set by course teams
LEARNER-3097

Updates the new bootstrap course home page to match the old course home page.

This reverts commit b541dfa3.

This reverts commit a1359535, reversing
changes made to 68d5fe89.

WL-1279

LEARNER-1923

Moves ENABLE_ENTERPRISE_INTEGRATION to settings.FEATURES,
and changes the default value to False.

LEARNER-2860

Implement a course dates fragment as a web view, currently we are using
the course info page to get the course dates section by parsing the
whole html page.

LEARNER-2769

ENT-704