Set Meta Data for Public Paperclip Images

Always set the cache control header for images that are going to be publicly served to allow taking advantage of browser caching.

has_attached_file :image,
:styles => { :large => "300x", :thumb => "100x", :small => "30x" },
 :storage => :s3,
 :s3_credentials => "config/s3.yml",
 :s3_permissions => :public_read,
 :s3_headers => { 'Cache-Control' => 'max-age=315576000', 'Expires' => 10.years.from_now.httpdate },