Update contributing doc with focused tests
Update contributing doc with focused tests

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