Add --ids-from option.
Remove useless & wrong args class variable.
Add concept of file mode.
Implement file mode.
Fix typo.
Handle stale session data.
Correctly catch DoesNotExist.
Add session_key_totals ivar to keep track of sum of all sizes for a key

Keeping track of totals as we go along saves us the trouble of calculating
them in post-processing logic.
Update session_key_totals when processing sessions.
Order output by total size.
Ensure that options['verbosity'] is an int before doing int comparison.
Add README.md
Don't perform two full table counts on each batch.
Don't be too specific about how we'll address problems going forward.
More README tweaks.
Add expire_after arg to get_filtered_queryset.
Maintain max processed expire date in get_sessions_db.
Remove start accounting; use simpler batch size limit.
Handle boundary conditions around expire_dates.
Maintain list of keys that we've already processed.