Changing model fields from Booleans to NullBooleans to be Django 1.1 compliant.
Changing model fields from Booleans to NullBooleans to be Django 1.1
compliant.

caktus/rapidsms-decisiontree-app,eHealthAfrica/rapidsms-decisiontree-app,caktus/rapidsms-decisiontree-app,ehealthafrica-ci/rapidsms-decisiontree-app,ehealthafrica-ci/rapidsms-decisiontree-app,eHealthAfrica/rapidsms-decisiontree-app,caktus/rapidsms-decisiontree-app