Converted to class-based

git-svn-id: https://plugins.svn.wordpress.org/simple-attribution/trunk@862618 b8457f37-d9ea-0310-8a92-e5e31aec5664
Remove duplicates

git-svn-id: https://plugins.svn.wordpress.org/simple-attribution/trunk@862625 b8457f37-d9ea-0310-8a92-e5e31aec5664