title: grunt, cannot get express server running
body: <p>I am using grunt-express-server and grunt-open to start the express server and open it in browser.  the problem is server gets started, then seems got closed by itself. after open it in browser,  you will get cannot connect to localhost:9000</p>
  
  <pre><code>'use strict';
  
  process.env.NODE_ENV = process.env.NODE_ENV || 'development';
  process.env.PORT = process.env.PORT || 9000;
  //var config = require('./lib/config/config');
  
  module.exports = function(grunt){
  
      require('load-grunt-tasks')(grunt);
      require('time-grunt')(grunt);
  
      grunt.initConfig({
          coffee: {
              build: {
                  expand: true,
                  flatten: false,
                  cwd: './src',
                  src: ['**/*.coffee'],
                  dest: './',
                  ext: '.js'
              }
          },
          express: {
              options: {
                  port: process.env.PORT,
                  background: true
              },
              dev: {
                  options: {
                      script: 'app.js',
                      debug: false
                  }
              }
          },
          open: {
              server: {
                  url: 'http://localhost:&lt;%= express.options.port %&gt;'
              }
          }
  
      });
  
      grunt.registerTask('default', ['coffee', 'express', 'open']);
  };
  </code></pre>