* apply policy per-course, even if multiple courses share course and org fields
* keep descriptors separate in xml store, so that if two such courses
  change the same module in different ways, it works.  Such edits will need to
  merged on CMS import...
* add get_instance(course_id, location) method to replace get_item(location).
  Update all the call sites
* tests, including a 2nd toy course with same course and org.

Kimth/multiple fileupload

Fix broken dependency updates for wiki

Feature/bridger/new wiki

Kimth/multiple fileupload

Remove outdated hardcoded url from circuit simulator

Added new styles for sequence nav and reset some of the styles for inputs