Tests: test_node_application_write_before_writeHead reworked.

Added res.end() call in application and response status check.
Also, renamed to test_node_application_write_before_write_head.

test/node/write_before_write_head/app.js

@@ -3,4 +3,5 @@
 require('unit-http').createServer(function (req, res) {
     res.write('blah');
     res.writeHead(200, {'Content-Type': 'text/plain'});
+    res.end();
 }).listen(7080);