* feat: Course Apps API
This adds a new concept called course apps. These are exposed via a new
"openedx.course_app" entrypoint, which helps the LMS and studio discover such
apps and list them in a new rest api for the same.
These course apps will drive the pages and resources view in the course authoring
MFE. This system will track which apps are enabled and which are disabled. It
also allows third-party apps to be listed here by using the plugin entrypoint.
* Apply feedback from review
* For all files, from __future__ import unicode_literals.
* Add @python_2_unicode_compatible to both models.
* Test six.string_type(obj) for both models.
Also, fix some new pylint warnings and improve model repr methods.
MST-24
Create read-only serializer to handle User/UserProfile data
together.
Refactor GET accounts to use the new read-only joint serializer
Fix tests to check for new expanded user info
Update tests in teams/tests/test_views.py to test for both
public and private profiles on expands user
Update serializer to utilize the request object for creating absolute uris
