Add configuration model for enrollment refunds.
Use order info from otto in refund window calculation
Delete dupe tests. Extend tests to include window tests
Move ecom client from lib to djangoapps in openedx
This new endpoint is intended to replace enrollment API call used on the login+registration page. Instead of directly enrolling students, the view will contact the external e-commerce API (Oscar) to create a new order. Oscar will be responsible for completing the order and enrolling the student.
This behavior will only apply to course modes with associated SKUs. All other course mode enrollments will be processed directly by LMS.
