Update Gemspec description for new sitemap extensions.
Merge branch 'master' of github.com:kjvarga/sitemap_generator

* 'master' of github.com:kjvarga/sitemap_generator:
  added support for s3 region
Fix #108 and #104: Show the URL being pinged.  Ping the correct URL if there is no index file generated (e.g. when create_index is :auto and only one sitemap is generated.)
Update readme
Upgrade to 4.1.1