Change args to BackPAN::Index->new

[schwern]

update     If true, force an update.  If false, never update.
ttl             Time for the cache to live.
debug     Turn on debugging
releases_only_from_authors  Only the authors directory is considered for releases
cache_dir  The directory to put the cache
backpan_index_url  Where to get the BACKPAN index file

[schwern]

Done.