title: Detect that android app has been updated
body: <p>I need to find out a way to detect that my app has been updated from google play. 
  After the update I want to run some functions that should only be runned once (and only after update).</p>
  
  <p>Are there any events or broadcasts sent after google play has updated an app?</p>
  
  <p>Or is there another way to find out?</p>