UX-1642 Making visual tweaks and enhancements to the logistration form

Update newrelic agent for monitoring celery tasks

XCOM-45 Enrollment API supports creating modes other than honor.

Copy changes to the activation email

Downgrade CORS middleware warning to info

Certificates: Revising Web Templates + UI for Open edX Use

Fixing tests, cleaning up POST handler to be easier to read.

Wording fixed for unit test comments.

Validating event emission by the commerce app

Fixed CourseMode Filtering Bug

Added SKU column to CourseMode table in Django admin

Allow services to ignore user throttling. Set a more realistic throttle for users.

Commerce code has now been updated to exclude CourseMode objects with SKU set to empty string (in addition to null).

Remove useless override_settings of MODULESTORE

Add show/hide previews button to Content Libraries

Awais786/ecom 1162 ga event

Add missing import of override_settings to fix a broken test in courseware