Make this test stronger

* Test for case-insensitive sorting
* Hardcode some values rather than trying to be clever and potentially
  missing things by, say, forgetting that python sort is also
  case-sensitive by default
* Test having a user play in both seasons
Do my own sorting in Python, outside of Django

Making Django order_by case insensitive requires using the extra()
method of QuerySet and writing my own SQL to select out the fields
through multiple table joins. Or I could just do it in Python. I
can revisit this later if it appears to be a speed bottleneck.