Refining an FTP Site List Download

This script introduces a pair of functions for checking whether FTP sites are up. The refineFTPList() function will take in a list of FTP sites and returns a list of siteses are up. The refineFTPList() function will take in a list of FTP sites and returns a list of sites that are not down. The isFTPSiteUp() function checks a particular FTP site to see if it is up.