Use node-notifier instead of terminal-notifier

[MoOx]

Now that Window build of Atom is provided, you should use a cross-os notification system.
node-notifier will do that job pretty well I think.

[yujinakayama]

Actually I tried to use the node-nofitifer package (and some other similar node packages) when I created this package, but I chose to use the raw terminal-notifier because the existing node packages didn't provide an interface to terminal-notifier's -sender option.

That said, I agree that it would be better to use more generic package and support Windows. I'll think a solution for this.

[walles]

Not sure if it existed when you wrote this, but nowadays https://atom.io/docs/api/v1.0.0/NotificationManager seems to be how notifications should be done in Atom.