start refactoring grades call
wire up offline grading task, and add initial tests.
add test for grading task
add offline grading button to instructor dash
Optimize grading for unanswered but weighted problems.  Return exception when encountering Error modules when running as task.
Try calling reset_queries explicitly, to see if it helps with memory usage on celery worker.
Update tests that are affected by requirement that grades be precalculated.
Add support for generating memory dumps. Handle xmodules that don't load.
Add dump directory to try, where dev-worker has space.
Move location of memory dump call, and truncate grading to 1000.
Move location of memory dump call, and truncate grading to 1000.
Remove prefetch_related call from grading task.
Remove memory dumping, and add some more logging.
Add select_related calls when collecting grade/enrollment info
Fix broken import
Remove run_update_task, since that was replaced by run_main_task
Fix tests resulting from instructor task method signature changes during rebase.
Remove some old commented out code, enable memory analysis with dowser.
Re-add meliae memory dumps for loadtest
Fix version for meliae