Log Message:
Update from version 0.48 to 0.50.

Pkgsrc changes:
 o Add new required dependencies

Upstream changes:

0.50 Wed Jan 21 10:42:00 GMT 2009
    - add support for an expires header when putting an object to
      Net::Amazon::S3::Client::Object
    - make all the classes immutable
    - add query_string_authentication_uri() to
      Net::Amazon::S3::Client::Object, suggested by Meng Wong

0.49 Tue Jan 13 09:04:42 GMT 2009
    - add support for listing a bucket with a prefix to
      Net::Amazon::S3::Client::Bucket