if we have to reload a module and already have the descriptor, we don't need to refect the descriptor (which results in another DB round-trip. We just need the student state.

Make default value for format setting None, and force lms and cms to be explicit about a string default

add depth parameters when loading course and student-state caches. This will make fewer (but fatter) queries to the database

  - ops view for the desktop app to talk to
  - xmodule that talks to the foldit model and displays the student's state
  - grading tweak to make grade updates from an external service work:
    - Add an always_recalculate_grades property to XModuleDescriptor.

This cuts the number of queries in 6.002 courseware loads from ~650 to
~5-40. Still to do: cache CustomTag templates so that we only load them
once per request.

- get_module() contract says it can return None (e.g. if access control check failed)

The real fix would be to have yield_dynamic_descriptor_descendents return
things in the proper order, but I'm not entirely sure what's going on
there, and this is a bug on prod now.

- go through all students, all of their problems, save count for each answer
- return csv
- url exists, but no links to it yet
- Will need to integrate with Ike's new dashboard code

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