Remove Paperclip URL handlers

See ofn-security issue #33 for details.

config/initializers/paperclip.rb

@@ -1,3 +1,14 @@
 Paperclip::Attachment.default_options[:source_file_options] = {
   all: "-auto-orient"
 }
+
+url_adapters = [
+  "Paperclip::UriAdapter",
+  "Paperclip::HttpUrlProxyAdapter",
+  "Paperclip::DataUriAdapter"
+]
+
+# Remove Paperclip URL adapters from registered handlers
+Paperclip.io_adapters.registered_handlers.delete_if do |_proc, adapter_class|
+  url_adapters.include? adapter_class.to_s
+end