Workaround for the "Windows rough edge" regarding the deletion of directories

In the issue [joyent/node#4337](https://github.com/joyent/node/issues/4337) it is recommended to add an error handler to the Windows watchers and to ignore the error. That's what this fix does. It adds an error handler, if the platform is "win32". To reduce the impact of the workaround, the error is only ignored, if the corresponding item doesn't exist.