Run sanitize_key() on post_status, comment_status, and ping_status on the way...

Run sanitize_key() on post_status, comment_status, and ping_status on the way into the DB.  Props duck_. For trunk

git-svn-id: https://core.svn.wordpress.org/trunk@17404 1a063a9b-81f0-0310-95a4-ce76da25c4cd