Initial notifier component addition

Sending an early PR os that Stephanie and John can take a look, let me know what they think.

`mdn.notify` has two uses right now:

    *  `discover(parentElement)`: Finds notifications under a given parent (which would have been rendered with the initial server request), and adds close icon and other items accordingly.  Options are passed via separate `data-` attributes

    *  `growl(message, options)`:  Adds a growl message to the growl notification tray, options passed via said object.  

A `handle` is returned from creating the notification, with a few methods for updating the notification style/status, its message, and the ability to close the item.  You also (dangerously) get access to the element itself.

To Do:

    *  Decide if `mdn.Notifier` is where we want this to go.
    *  Apparently "icon-times" isn't available in our version of Font Awesome, so I'm using the trash can icon for deletion now.  Gross.  Need to either upgrade FA (may be difficult) or find a an image to use.
    *  Convert $.fn.mozNotifier uses to this new component.

Let me know what you think!
The <var>onclick</var> callback doesn't work for me. I could be missing something, but I don't see it used anywhere.