Introduce two new message for gossip proto

To be able to run state transfer across the gossiping peer
two message type has been added into gossip protos.

Change-Id: Iae4b155115a07175b098aab9f9fe5df470a2fc3a
Signed-off-by: Artem Barger <[email protected]>

Author: C0rWin

gossip/proto/message.pb.go

@@ -38,6 +38,9 @@ message GossipMessage {
 
         // ConnEstablish, used for establishing a connection
         ConnEstablish conn = 12;
+
+        RemoteStateRequest stateRequest = 14;
+        RemoteStateResponse stateResponse = 15;
     }
 }
 
@@ -118,4 +121,12 @@ message Member {
     bytes pkiID     = 3;
 }
 
-message Empty {}
+message RemoteStateRequest {
+    repeated uint64 seqNums = 1;
+}
+
+message RemoteStateResponse {
+    repeated Payload payloads = 1;
+}
+
+message Empty {}