product-release-finder should make sane milestone names

Many releases that are found have capital letters. User who setup the milestones and releases by hand know to lowercase them, the prf should do the same for 0.8.1.0_de_DE:
    2009-06-30 21:16:41 ERROR Could not successfully process URL
        http://www.marcus-furius.com/files
        /FuriusIsoMount/furiusisomount-0.8.1.0_de_DE.tar.gz for furiusisomount/mono
         -> http://staging.launchpadlibrarian.net/28530799/53jA7g7eKylc1mW3oUipeyv2qR.txt
              (new row for relation "milestone" violates check constraint "valid_name"

Many releases on other sites may have underscores. The release files may have an underscore in Launchpad. The milestone name cannot have an underscrore. The prf should replace the underscore with a hyphen when it creates the milestone name.
    2009-06-30 19:25:04 ERROR Could not successfully process URL
        http://ftp.netrek.org/pub/paradise/client/client-2.4p1A.tar.gz
        for netrek-archive/paradise
        -> http://staging.launchpadlibrarian.net/28530764/53jA7g7eKylc1mW3oUipeyv2qR.txt
            (new row for relation "milestone" violates check constraint "valid_name"
)