message: Increase auth_token size according to spec
diff: @@ -418,8 +418,9 @@ void ProtocolHandlerImpl::SendStartSessionAck(
  sync_primitives::AutoLock lock(auth_token_map_lock_);
  auto it = auth_token_map_.find(policy_app_id);
  if (it != auth_token_map_.end()) {
  - char auth_token[256];
  - strncpy(auth_token, it->second.c_str(), 255);
  + char auth_token[65536];
  + strncpy(auth_token, it->second.c_str(), 65535);
  + auth_token[sizeof(auth_token) - 1] = '\0';
  bson_object_put_string(&params, strings::auth_token, auth_token);
  }
  }
  