Many bug fixes:

- Bug #17458 fixed. Normalize the :expires_in option to always be an integer even if the actual object passed in is a proxy to an integer, such as is the case with 2.hours from ActiveSupport which is actually an instance of ActiveSupport::Duration. Reported by [Steve Kickert steve@riverocktech.com] />
- Bug #19158 fixed. Don't prepend leading slash onto bucket name when deleting a bucket with the :force => true option.

- Bug #17628 fixed. Don't ignore :use_ssl => false in url_for when the connection is established over ssl. Reported by [Tom Fixed (tkat11)]

- Bug #13052 fixed. Appease some proxies by always including a Content-Length with all requests. Reported by [James Murty (jmurty)]

- Bug #13756 fixed. Attributes that are false should not raise NoMethodError in Base#method_missing. Fixed by [Scott Patten]

- Bug #19189 fixed. No longer reference Date::ABBR_MONTHS constant which was removed in Ruby 1.8.6. Reported by [Khurram Virani (kvirani)]

- Bug #20487 fixed. If a request fails and is retried, only escape the request path the first time. Reported by [anonymous]

- Replace ad-hoc S3Object.copy method with newly support built in API call.

- Do not make connections persistent by default. This "feature" causes far more broken pipes than it is worth. Use with caution.