title: Granular 'public' settings on uploaded files with Fog and Carrierwave
body: <p>I am creating a rails app that lets an administrator upload photos that are optionally publicly displayed.  For the upload / storage process I am using the Carrierwave gem along with the Fog gem and S3.  The issue is that in order to get this all working, I have to make every file uploaded to the s3 bucket public.  Is there a way to make files public / private on a file-by-file basis?  Also, if this file-by-file granularity is possible, can it extend down to versions of images (created by automatic Carrierwave resizing)?</p>
  
  <p>Currently, I have the following line in my carrierwave initializer:</p>
  
  <pre><code>  config.fog_public = true
  </code></pre>