Use path_style option to make Fog::Storage honor url_host customization to s3.amazonaws.com

See fog/fog#1571 for problems with using dot-containing subdomains in S3, which can result in "hostname does not match the server certificate (OpenSSL::SSL::SSLError)" error in Excon. Using the path style avoids this issue, but it must be enabled in Fog::Storage.new when appropriate.