Merge pull request #32 from edTheGuy00/patch-1

Update RxFirebaseDatabase.java

Author: FrangSierra

app/src/main/java/durdinapps/rxfirebase2/RxFirebaseDatabase.java

@@ -56,6 +56,8 @@ public void subscribe(final FlowableEmitter<DataSnapshot> emitter) throws Except
                public void onDataChange(DataSnapshot dataSnapshot) {
                   if (dataSnapshot.exists()) {
                      emitter.onNext(dataSnapshot);
+                  } else {
+                     emitter.onComplete();
                   }
                }
 
@@ -486,4 +488,4 @@ public static <T> Flowable<RxFirebaseChildEvent<T>> observeChildEvent(
       ? extends RxFirebaseChildEvent<T>> mapper) {
       return observeChildEvent(query, BackpressureStrategy.DROP).map(mapper);
    }
-}
+}