Add attached file info to Paymentmethod model
user
```ruby
Spree::PaymentMethod.class_eval do
  attr_accessible :icon

  has_attached_file :icon,
    styles: { mini: '32x32>', normal: '128x128>' },
    default_style: :mini,
    convert_options: { all: '-strip -auto-orient -colorspace sRGB' }

  include Spree::Core::S3Support
  supports_s3 :icon
end
```
assistant