Support 308 status redirect

Author: janko

lib/open-uri.rb

@@ -356,7 +356,8 @@ def OpenURI.open_http(buf, target, proxy, options) # :nodoc:
     when Net::HTTPMovedPermanently, # 301
          Net::HTTPFound, # 302
          Net::HTTPSeeOther, # 303
-         Net::HTTPTemporaryRedirect # 307
+         Net::HTTPTemporaryRedirect, # 307
+         Net::HTTPPermanentRedirect # 308
       begin
         loc_uri = URI.parse(resp['location'])
       rescue URI::InvalidURIError