title: Missing requirement when using carrierwave and fog to upload file to S3
body: <p>I got this error <code>Missing required arguments: aws_access_key_id, aws_secret_access_key</code>. That seems weird because I already added carrierwave.rb in initializers folder. The access/secret key works perfectly when I use <strong>aws-sdk</strong></p>
  
  <pre><code>CarrierWave.configure do |config|
    config.fog_credentials = {
      provider: "AWS",
      aws_access_key_id: ENV["PUB-KEY"],
      aws_secret_access_key: ENV["SEC-KEY"]
    }
    config.fog_directory = ENV["mybucket"] 
  end
  </code></pre>