I am attaching the new version of the module.
I've took davegan's version, added his extra table to the install code, fixed the uninstall code, and renamed the module to uc_affiliate2.
This will allow it to be submitted to drupal.org

You should uninstall the old module before you install this one, since it's technically a new module.
However, the tables haven't changed, so you can rename your old ones from uc_affiliate_* to uc_affiliate2_* or just reinsert the data, and nothing will be lost.