gecko/services/notifications

Here lies most of the moving parts for push notifcations in the browser. DOM
and UI bindings will live elsewhere; these files deal with talking to the API,
storing messages, and creating persistent connections to the notification
server.

Structure:

services.js::Service
  This is a singleton that manages API calls and message storage. It's an
  instance of the NotificationSvc class. Messages and state are persisted to a
  JSON file on disk.