title: Firebase listeners when offline and not authenticated
body: <p>Is this behavior correct? </p>
  
  <p>I'm using firebase as local database, and also  for (optional) authentication and (optional) sync.</p>
  
  <p>When a user hasn't authenticated yet, and I set  .goOffline(), the ValueEventListener (either with and ValueEventListener or addListenerForSingleValueEvent)  never gets called when I try adding stuff (locally, because I am always offline). Note that the ChildEventListener does get called in this case. </p>
  
  <p>If the user authenticates, and I still set goOffline(), the ValueEventListener and the ChildEventListener both get called correctly, as expected. </p>
  
  <p>I am wondering why this happens (only ChildEventListener getting called when not authenticated), and wouldn't mind any clarification if I'm doing something wrong. </p>
  
  <p>Secondly, is the local cache a database or does it only store a list of transactions? In other words, if I always stay offline, will firebase have to go through thousands of transactions history to deliver what I want? </p>
  
  <p>Thanks! </p>