Node.js: added reference count increment for the Unit object.

We increase the number to the Unit object so that it lives forever.
This is necessary so that the garbage collector does not delete the Unit object.

src/nodejs/unit-http/http_server.js

@@ -333,6 +333,8 @@ Server.prototype.run_events = function (server, req, res) {
         });
 
         Promise.resolve().then(() => {
+            req.emit("finish");
+
             if (res.finished) {
                 unit_lib.unit_response_end(res);
             }