fix that lxml was requested before warning users that lxml has to be installed
fix that lxml was requested before warning users that lxml has to be installed

fiuba08/robotframework,waldenner/robotframework,fiuba08/robotframework,ldtri0209/robotframework,fiuba08/robotframework,ldtri0209/robotframework,waldenner/robotframework,waldenner/robotframework,ldtri0209/robotframework,ldtri0209/robotframework,fiuba08/robotframework,ldtri0209/robotframework,fiuba08/robotframework,waldenner/robotframework,waldenner/robotframework