fixed get_cartodbfied_tables when there is not tables in user metadata database
fixed get_cartodbfied_tables when there is not tables in user metadata database

CartoDB/cartodb,codeandtheory/cartodb,CartoDB/cartodb,nuxcode/cartodb,splashblot/dronedb,dbirchak/cartodb,UCL-ShippingGroup/cartodb-1,UCL-ShippingGroup/cartodb-1,thorncp/cartodb,nyimbi/cartodb,thorncp/cartodb,CartoDB/cartodb,nuxcode/cartodb,bloomberg/cartodb,splashblot/dronedb,DigitalCoder/cartodb,UCL-ShippingGroup/cartodb-1,splashblot/dronedb,raquel-ucl/cartodb,future-analytics/cartodb,CartoDB/cartodb,bloomberg/cartodb,future-analytics/cartodb,dbirchak/cartodb,DigitalCoder/cartodb,nyimbi/cartodb,raquel-ucl/cartodb,nyimbi/cartodb,CartoDB/cartodb,raquel-ucl/cartodb,thorncp/cartodb,UCL-ShippingGroup/cartodb-1,DigitalCoder/cartodb,DigitalCoder/cartodb,raquel-ucl/cartodb,codeandtheory/cartodb,dbirchak/cartodb,bloomberg/cartodb,nyimbi/cartodb,bloomberg/cartodb,dbirchak/cartodb,thorncp/cartodb,nuxcode/cartodb,future-analytics/cartodb,DigitalCoder/cartodb,raquel-ucl/cartodb,nuxcode/cartodb,future-analytics/cartodb,codeandtheory/cartodb,bloomberg/cartodb,codeandtheory/cartodb,future-analytics/cartodb,codeandtheory/cartodb,splashblot/dronedb,dbirchak/cartodb,nuxcode/cartodb,UCL-ShippingGroup/cartodb-1,nyimbi/cartodb,splashblot/dronedb,thorncp/cartodb