title: Delete Objects in Realm using cascade Relationship
body: <p>I have a Class "Person":RLMObject. Now this Class has a property "Dog":RLMObject.
  When i delete "Person" object from Realm, it doesn't automatically delete the "Dog" associated with it.</p>
  
  <p>Is there any delete rule in Realm like in Core Data? Help me to resolve this issue.</p>
  
  <p>Thanks!</p>