messaging.install doensn't remove filter_format

messaging_install() runs _messaging_install_create_filter();

messaging_uninstall() doesn't remove it.

If you uninstall messaging and then re-install, you'll get an error:

user warning: Duplicate entry 'Messaging plain text' for key 2 query: INSERT INTO filter_formats (name, cache) VALUES('Messaging plain text', 0) in /workspace/tysc/thruyou_drupal/sites/all/modules/messaging/messaging.install on line 60.