Adds a course_ids api that can filter by user role, since the courses
api could not perform well enough for this, and returned much more
data than we need.

Additionally, adds a LazyPageNumberPagination to provide more accurate
counts in the pagination response when using LazySequence with the
queryset.

BOM-897

This will remove imports from __future__ that are no longer needed.

https://docs.python.org/3.5/library/2to3.html#2to3fixer-future

Django 1.10 deprecation fix for Hackathon XIX
Addresses PLAT-1397

This reverts commit a1419b15.

The license for course run content is now stored on the CourseOverviews model and exposed via the Course API.

LEARNER-2791

This reverts commit c6b6d0bc, reversing
changes made to fa2b1ae4.

ECOM-4013

ECOM-3994

- Remove escaping in display_name_with_default
- Move escaped version to deprecated display_name_with_default_escaped
- Does not include any other changes to remove double-escaping

Thanks to agaylard who initiated this work:
https://github.com/edx/edx-platform/pull/10756

TNL-3425

MA-1661

* Catalog results are now paginated
* Implements the new namespaced pagination described at
  https://openedx.atlassian.net/wiki/pages/viewpage.action?pageId=47481813
* API level code returns pythonic business objects
* View layer performs serialize at the view layer
* Convert views to use DRF generic views
* Removes an unintentional authentication decorator that caused
  the detail endpoint to return a 401 for anonymous users

MA-1724