Drilling down works on a functional level. Gotta set up interface and
tests.

On a related note, TAKE THAT DJANGO FILTERS.
Left in a wee bit of debugging code.
Basic interface done.
Interface is most of the way there.
Added unit tests.
Should be ready to go!
Merge branch 'admin-date-hierarchy' of git://github.com/powersurge360/django-admin2 into powersurge360-admin-date-hierarchy