Don't die if announce URL not found.

rtorrent state "torrent" files don't have an announce URLs but don't care if they are added.
Now we can reannounce torrents that are already running.

Stop rtorrent, reannounce both state files (and the tied torrent if exist)
Delete the <HASH>.torrent.libtorrent_resume
??????
Profit!!!
STY Use if/then instead of try/except