title: detect addition, deletion of contact in android
body: <p>How do I detect if there was a change in the contact database in Android. 
  Assuming, the application needs to trigger a function if a new contact is added or existing contact is modified or deleted. </p>
  
  <p>The app need to know of any state changes to the contact database. 
  Appreciate any help in this regards. </p>
  
  <p>Thanks</p>