Added more node tests. Small refactoring of Netowkr and handler.

network/proto/network.proto

@@ -36,13 +36,11 @@ message PeerResponse {
 message TopologyRequest {
         // node id
         string id = 1;
-        // topology depth
-        uint64 depth = 2;
 }
 
 // TopologyResponse is returned by Topology
 message TopologyResponse {
-        Topology topology = 1;
+        Peer topology = 1;
 }
 
 // Node is network node
@@ -53,14 +51,6 @@ message Node {
         string address = 2;
 }
 
-// Topology is used to nnounce node neighbourhood
-message Topology {
-        // network node
-        Node node = 1;
-        // neighbours
-        repeated Node nodes = 2;
-}
-
 // Connect is sent when the node connects to the network
 message Connect {
         // network mode