* still needs better error checking and testing

* specify in tabs list in course policy
  - active page tracking now done in tabs.py
  - properly handle the fact that there may be multiple textbooks

* Still need:
  - wiki pages
  - (if that's delayed, special-case syllabus support)

also show pid in migration and instructor dashboard views for thread debugging

- on first visit to courseware, go straight to first section of first chapter
- after, clicking on courseware tab sends you most recent chapter, with a link to the most recent section
  (not to section because that might be confusing, and you might want to do something else (e.g. do homework instead of watch videos)
- Moved course errors into instructor tab.

- for internal cs50 until we have grade integration set up (only really needed for external version)

Add support for discussion_link attribute in course policy files as a kludge to support CS50's external forums

functionality - grade dump and download as csv, manage staff list,
force reload of course from xml

Create a new template that inherits from course_navigation.html to avoid repeating the course navigation template and augment it with the new post button.