Ubercart Attribute Node Import

Adds Ubercart Attribute options for node import.

I originally built this for some immediate needs. When I was using this module on the project for which I created it, it was working great. It's definitely not production-ready, so be sure to perform a database backup before using it!

I've moved to Drupal 7 for all development and have moved to Drupal Commerce. That said, I'd be happy to help with any minor tweaks, bugfixes, etc., but I won't be able to devote much time to this module.

Note: I'm posting this project long after I wrote the code, which is provided mainly for reference purposes. I've undoubtedly learned better ways to do things in Drupal/PHP since writing this code, but I do not intend to update/modify this code unless I have specific requests to do so.