Bring unl_schema() up to date with latest unl_sites table changes so that a fresh drupal install will work; Fix unl_update_ functions by removing multiple adds of clean_url column which causes update to fail

git-svn-id: file:///tmp/wdn_thm_drupal/branches/drupal-7.x@224 20a16fea-79d4-4915-8869-1ea9d5ebf173