title: How to use Background agent to send toast notification?
body: <p>I am working on windows development &amp; I am displaying the items on the emulator by using a web service. 
  Now I want to send a toast notification when an item added to the service. Already I worked with push notifications. But It’s generating push channel URL when app is initialized. 
  I don’t want to use this channel URL. So I tried Background Agent &amp; Shell Toast to send the notification. Its working fine for static data. How can I add dynamic data to back ground agent which is coming from web service?
  One more thing is, there are two things like PeriodicTask &amp; ResourceIntensiveTask. How can I use this to send a toast notification by using Background Agent?</p>