9/1/13 evening:
1.  Modified DAO GetDataElementByCode to fix field name.
2.  Modified dhis_datavaluetemplate so that dataelement_id,
categoryoption_id and reporttemplate_id can be null.  Modified hbm
similarly.
3.  Changes to DhisXmlUtils:buildObjects to handle unanticipated nulls
(to be investigated)
4.  Change to DhisXmlUtilsTest to use and save in actual DB, working for
allPatients and unidentified cohort definitions