Set the User-Agent when downloading
Set the User-Agent when downloading

Some websites will return 403 if there is no User-Agent in the request.
open-uri sets "ruby", but some websites won't consider it a valid
User-Agent (ironically, ruby-toolbox.com won't).

See https://github.com/carrierwaveuploader/carrierwave/issues/1459.

janko-m/shrine,janko-m/shrine