Removed census.py's dependence on json.
Removed census.py's dependence on json.

mathstuf/tangelo,ecohealthalliance/tangelo,ecohealthalliance/tangelo,ecohealthalliance/tangelo,aashish24/tangelo,mathstuf/tangelo,aashish24/tangelo,aashish24/tangelo,mathstuf/tangelo,Kitware/tangelo,Kitware/tangelo,Kitware/tangelo