Pass filename param to UploadIO.new

@steved555 Adding filename to UploadIO.new. I've fixed up the specs a bit but the one I've commented out just wouldn't pass for me. Not sure what needs to be done about that.

In order to get the specs running I had to bundle update with a newer version of actionpack. I haven't checked in the update Gemfile.lock as I didn't think it was worth updating a load of other dependencies just for these infrequently used specs.

There may be less issues getting this into the master branch than there is with 1.2.

Let me know what you think