service/cw_id_watcher should be renamed

[pwaller]

At the moment there is a component called LogWatcher. However, it doesn't do any kind of watching. When called, it simply associates the Batch log ID with the CloudWatchLogs ID. This could be made clearer with a better name. It's also worth considering moving the package.

See also this comment.

Some possible candidates:

• cmd/cron/logassoc
• service/cron/logassoc
• service/locassoc

Feel free to suggest more.