plug in LedgerWindow

fixes #872

tests/data_replicator.rs

@@ -24,6 +24,7 @@ fn test_node(exit: Arc<AtomicBool>) -> (Arc<RwLock<Crdt>>, Ncp, UdpSocket) {
     let d = Ncp::new(
         &c.clone(),
         w,
+        None,
         tn.sockets.gossip,
         tn.sockets.gossip_send,
         exit,

tests/multinode.rs

@@ -43,6 +43,7 @@ fn converge(leader: &NodeInfo, num_nodes: usize) -> Vec<NodeInfo> {
     let ncp = Ncp::new(
         &spy_ref,
         spy_window,
+        None,
         spy.sockets.gossip,
         spy.sockets.gossip_send,
         exit.clone(),