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

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