Desktop Notification Node

[Growl](http://growl.info/) and [Libnotify](https://developer.gnome.org/libnotify/) are unified desktop notification systems. This node allows to send notifications to the local desktop, using visionmedia's [node-growl](https://github.com/visionmedia/node-growl) module, that supports both growl and libnotify. Note that this does not include native windows notifications - windows users would have to install growl by hand. Linux users, consider [this wiki](https://wiki.archlinux.org/index.php/Desktop_Notifications).