Instead, use a class attribute to define test behavior. This allows for
easier addition of new mixins over time.

- has_course_access renamed to has_course_author_access for clarity
- Changed doc string to clearly state that it determines whether or not
  a user has write access to a course

for visual indent

Refactor get_parent_locations STUD-1663

[LMS-2757]

This commit adds all of cms.

These keys are now objects with a limited interface, and the particular
internal representation is managed by the data storage layer (the
modulestore).

For the LMS, there should be no outward-facing changes to the system.
The keys are, for now, a change to internal representation only. For
Studio, the new serialized form of the keys is used in urls, to allow
for further migration in the future.

Co-Author: Andy Armstrong <andya@edx.org>
Co-Author: Christina Roberts <christina@edx.org>
Co-Author: David Baumgold <db@edx.org>
Co-Author: Diana Huang <dkh@edx.org>
Co-Author: Don Mitchell <dmitchell@edx.org>
Co-Author: Julia Hansbrough <julia@edx.org>
Co-Author: Nimisha Asthagiri <nasthagiri@edx.org>
Co-Author: Sarina Canelake <sarina@edx.org>

[LMS-2370]

STUD-1006

on new Locators to make it clear that they have a different syntax
than Location.course_id altho they represent the same info.

Ensure user admin screen gets the union of all possibly matching group names.
Smarter default group naming.
STUD-1003