Use URI.open to assign external cached attachments

We were having issues with cached attachments and external services.

A `Tempfile` is returned by `URI.open` when using S3, so we're dealing
with this case as well.

app/models/concerns/attachable.rb

@@ -37,7 +37,7 @@ module Attachable
     if Paperclip::Attachment.default_options[:storage] == :filesystem
       File.open(cached_attachment) { |file| self.attachment = file }
     else
-      self.attachment = URI.parse(cached_attachment)
+      self.attachment = URI.open(cached_attachment)
     end
   end
 

app/models/concerns/has_attachment.rb

@@ -9,7 +9,7 @@ module HasAttachment
       alias_method :"paperclip_#{attribute}=", :"#{attribute}="
 
       define_method :"#{attribute}=" do |file|
-        if file.is_a?(IO)
+        if file.is_a?(IO) || file.is_a?(Tempfile) && !file.is_a?(Ckeditor::Http::QqFile)
           send(:"storage_#{attribute}").attach(io: file, filename: File.basename(file.path))
         elsif file.nil?
           send(:"storage_#{attribute}").detach