[ENT-386] Styling Issues on new registration page

[ENT-378] Remove code for custom header logo

EDUCATOR-62 Fix question text wrapping in IE11

Add instructions.

LEARNER-859: Updating styling on the course updates page

Mark test as flaky, and remove flaky from a fixed test.

Fix for LEARNER-859: Updating styling on the course updates page to more clearly differentiate between multiple updates. Specifically:
- Updated styling on date in the top left corner
- Added horizontal line between updates
- Removed ability to toggle updates on and off
- Cleaned up code to always show all updates:

LEARNER-881: Per-course rollout configuration model

EDUCATOR-511

More specific grade_course logging

Sstudent/course policy event

More celery logging

Mask grades on progress page according to show_correctness setting

Fix the activation email support link in the dashboard sidebar

Defaulting to a plaintext response makes no sense for an endpoint that is intended to be used by machines for testing. The endpoint now returns JSON only unless a redirect action is triggered.

[ENT-381] Conform to WCAG 2 AA contrast minimums for Google OAuth.

LEARNER-923 Make Pattern Library support tabs transparent

Christina/ed 427 again

EDUCATOR-396

Django Signal Handler for GRADING_POLICY_CHANGED

https://openedx.atlassian.net/browse/EDUCATOR-393

Reorder Studio imports using isort

Reorder imports using isort (except lms and cms)

The programs detail page now always makes a call to the Credentials API to check for program credentials, regardless of whether the user has earned a course certificate. The course certificate constraint adds an additional burden to testing in exchange for slightly decreased load on the API. The cost outweighs the benefit given the limited traffic to this page.

LEARNER-1103

add indices to item nodes when dumping to neo4j