add a command line option to disable ZMQ server

src/daemon/command_line_args.h

@@ -122,6 +122,11 @@ namespace daemon_args
     }
   };
 
+  const command_line::arg_descriptor<bool> arg_zmq_rpc_disabled = {
+    "no-zmq"
+  , "Disable ZMQ RPC server"
+  };
+
 }  // namespace daemon_args
 
 #endif // DAEMON_COMMAND_LINE_ARGS_H