message: fix state proof parsing, tests coming
diff: @@ -425,7 +425,7 @@ fn _parse_reply_for_sp(json_msg: &SJsonValue, data: Option<&str>, parsed_data: &
  return Err("No ledger length for this proof".to_string())
  };
  - (proof, root_hash, KeyValueSimpleDataVerificationType::MerkleTree(len), parsed_data["multi_signature"].clone())
  + (proof, root_hash, KeyValueSimpleDataVerificationType::MerkleTree(len), parsed_data["state_proof"]["multi_signature"].clone())
  };
  let value: Option<String> = match _parse_reply_for_proof_value(json_msg, data, parsed_data, xtype, sp_key) {
  @@ -1473,8 +1473,10 @@ mod tests {
  "ledgerSize": 2,
  "rootHash": "123",
  "txn": {"test1": "test2", "seqNo": 2},
  + "state_proof": {
  "multi_signature": "ms"
  }
  + }
  });
  let nodes_str = base64::encode(&json!(["1", "2"]).to_string());
  @@ -1538,8 +1540,10 @@ mod tests {
  // "ledgerSize": 2,
  "rootHash": "123",
  "txn": {"test1": "test2", "seqNo": 2},
  + "state_proof": {
  "multi_signature": "ms"
  }
  + }
  });
  assert!(super::parse_generic_reply_for_proof_checking(json_msg,
  @@ -1556,8 +1560,10 @@ mod tests {
  "ledgerSize": 2,
  "rootHash": "123",
  // "txn": {"test1": "test2", "seqNo": 2},
  + "state_proof": {
  "multi_signature": "ms"
  }
  + }
  });
  let nodes_str = base64::encode(&json!(["1", "2"]).to_string());
  