Pass on `resource_type` to `Cloudinary::Utils.cloudinary_url` with stored `attachinary_file#resource_type`

[rafb43]

I believe this should be the default behavior, to avoid uploading .ppt, .xsl, etc... with raw and then not being able to serve them because the url is image by default as shown in https://github.com/cloudinary/cloudinary_gem/blob/master/lib/cloudinary/utils.rb#L93