Media Category function.php From http://premium.wpmudev.org/blog/wordpress-media-categories-tags/?nlv=d&utm_expid=3606929-35.im_xHH3rTkmdlc6O7wpMUQ.3&utm_referrer=https%3A%2F%2Fwww.google.it%2F
// add categories for attachments
function add_categories_for_attachments() {
register_taxonomy_for_object_type( 'category', 'attachment' );
}
add_action( 'init' , 'add_categories_for_attachments' );
// add tags for attachments
function add_tags_for_attachments() {
register_taxonomy_for_object_type( 'post_tag', 'attachment' );
}
add_action( 'init' , 'add_tags_for_attachments' );