drop head elements and put visited url in the bucle, not inside of extracting information procedure
reorganization of visited[url] -> better at beggining of bucle because it's at the beggining when we visit the url, not at the final. Moreover, secondary bucle procedures could increase very much the time and then visited[url] = time.time() were be not real
urlparse -> updated all_tasks.txt. urllib.parse does not play 'very well' with 'localhost:8080/a' saying scheme is localhost. Aghhh!