title: missing required option :name
body: <p>I am trying to set up AWS, and carrierwave to upload pictures from my website. I keep getting the error 'missing required option :name' when I try to upload/update the posts though. I have followed tutorials to set up my S3 account and to get carrierwave.rb set up. Please let me know if you have any ideas!</p>
  
  <p>carrierwave.rb</p>
  
  <pre><code>CarrierWave.configure do |config|
   config.storage    = :aws
   config.aws_bucket = ENV['S3_BUCKET_NAME']
   config.aws_acl    = 'public-read'
   config.aws_authenticated_url_expiration = 60 * 60 * 24 * 7
   config.aws_attributes = {
     expires: 1.week.from_now.httpdate,
     cache_control: 'max-age=604800'
   }
  
   config.aws_credentials = {
     access_key_id:     ENV['AWS_ACCESS_KEY_ID'],
     secret_access_key: ENV['AWS_SECRET_ACCESS_KEY'],
     region:            ENV['AWS_REGION']
   }
  end
  </code></pre>
  
  <p>.env example</p>
  
  <pre><code>S3_BUCKET_NAME=*****
  AWS_ACCESS_KEY_ID=*****
  AWS_SECRET_ACCESS_KEY=*****
  AWS_REGION=*****
  </code></pre>
  
  <p>portfolio_uploader.rb</p>
  
  <pre><code>class PortfolioUploader &lt; CarrierWave::Uploader::Base
  
    storage :aws
  
    def store_dir
      "uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
    end
  
    def extension_white_list
      %w(jpg jpeg gif png)
    end
  end
  </code></pre>