fix migration to not depend on model.meta. 
fix migration to not depend on model.meta. 
CivicVision/datahub,CivicVision/datahub,johnjohndoe/spendb,USStateDept/FPA_Core,nathanhilbert/FPA_Core,openspending/spendb,USStateDept/FPA_Core,openspending/spendb,pudo/spendb,USStateDept/FPA_Core,johnjohndoe/spendb,nathanhilbert/FPA_Core,pudo/spendb,spendb/spendb,CivicVision/datahub,nathanhilbert/FPA_Core,johnjohndoe/spendb,pudo/spendb,spendb/spendb,spendb/spendb,openspending/spendb