CLC-2498 Add course sites to My Academics feed for instructors

Requirement for:
https://jira.ets.berkeley.edu/jira/browse/CLC-2498
https://jira.ets.berkeley.edu/jira/browse/CLC-2631

This adds bCourses and bSpace class sites to the "teaching_semesters" section of the academics JSON feed, as shown in: https://github.com/ets-berkeley-edu/calcentral/blob/master/public/dummy/json/academics.json

This feed is used by the My Academics class pages and by the bCourse Course Provisioning app. Changing their UX to surface the new class site links is a follow-up task.