fs.watch confusing behaviors under linux.

[NStal Loit]

`fs.watch` are not capable to tell difference between the folder change or the child change when watching the folder. 

When I have a folder `bob`,  and a file `bob/bob` under the folder.  Both unlink `bob/bob` or rmdir `bob` make the same result invoking the callback("rename","bob"); 

I create a gist to demostrate this issue.

https://gist.github.com/NStal/d2b4ce826a47fc149812

Any one has some ideas or should fire a bug report? Thanks so much.