support attachments that come from a form upload
support attachments that come from a form upload

* i don't know why this functionality was removed,
  or if it probably is replaced with something else
  or used differently now.

* i added back the behavior like it in older versions
  of dm-paperclip, see http://is.gd/Snwx

Signed-off-by: Ken Robertson <470bc578162732ac7f9d387d34c4af4ca6e1b6f7@qgyen.net>
krzyzanowskim/dm-paperclip-s3,dxg/dm-paperclip