fsnotify moving notice

Go 1.3 will include os/fsnotify in the standard library with a new [API](http://goo.gl/MrYxyA). 

* Import `code.google.com/p/go.exp/fsnotify` ([GoDoc](http://godoc.org/code.google.com/p/go.exp/fsnotify)) for the latest API under development.
* Continue importing `github.com/howeyc/fsnotify` ([GoDoc](http://godoc.org/github.com/howeyc/fsnotify)) for the stable API.
* [Report Issues](https://code.google.com/p/go/issues/list?q=fsnotify) to go.exp/fsnotify after testing against `code.google.com/p/go.exp/fsnotify`