Add event emitted for directories that don't match the pattern

The `add` event is emitted for added directories, even if they don't match the provided pattern (the test added in 80271bd8010e08903d0fe4bcf2cb1746e7f30a7c asserts this behavior).

Incidentally, this causes the ["finicky" `addedLater` test](https://github.com/shama/gaze/blob/623c7fa7b773572b4821b4ee121222d0db0ddfbd/test/matching_test.js#L90).  The test does two writes, presumably to get an `add` event followed by a `change` event.  However, there are two `add` events for the first write (one for `newfolder` and one for `newfolder/added.js`).  So the test finishes before the second write, and the `newfolder` is created after the cleanup.