Demo Notification Service

This is a simple demo service provider that reads notifications from a file.  It provides a <code>setActive(boolean)</code> method (default is true) for toggling it on and off at runtime.

Also note the DemoNotificationService has a date adjustment feature to keep the dates relevant so the dates you see in the demo JSON do not represent current dates. They provide a fixed date that DemoNotificationService can provide an offset to.