When creating an instructor task total_num_items may change between the
time it and the number of subtasks is calculated and the time the
subtasks are actually queued (all of this cannot happen in one transaction).
In such a case the extra items are distributed among the subtasks of the
last query.

LMS-2090

LMS-1744

that are not present in a given student's gradeset.

General code cleanup and addition of comments.

Instructor dashboard API unit tests.

LMS-58

Hook up display of grade files ready for download to new instructor dashboard.

LMS-58

Adds xblock handler_url support to the LMS, and makes handle_ajax use
that code.

[LMS-230] [LMS-229]

Add cache-based locking to subtasks to ensure that the same task is not running in two workers at the same time.

Add cache-based locking to subtasks to ensure that the same task is not running in two workers at the same time.