List all courses during OAut2/OpenID Connect

Previously, only courses respective to the branded instance were returned.

AN-3610
Overview and configuration for cohorts feature
Merge pull request #5327 from edx/ahodges/doc/cohorts

Ahodges/doc/cohorts
Merge pull request #5486 from rocha/list-all-visible-courses

Use all courses during OAut2/OpenID Connect
Use:
	CourseLocator.from_string()
instead of:
	SlashSeparatedCourseKey.from_deprecated_string()
to construct the course_key for which the auto-created user is registered.
Add bulk_operations() wrapper around course progress view.
Don't fetch python libs if there's no python code
in the capa problem.
Use bulk operations on get_course_by_id and courseware
Wrap course info and dashboard in bulk ops wrapper to reduce Mongo calls.
Cache modules in split bulk ops