title: Not able to run selenium grid and nightwatch
body: <p>I'm trying to run test environment where each component is in a docker (nightwatchjs, browsers, selenium server).
  But now I'm stuck in finding right "setup". I get "Connection is refused is Selenium started" all the time. 
  And it is weird because I set up webdriverio in a similar way and it works (repo forked from hulilabs repo).
  <a href="https://github.com/MichalDulemba/webdriverio" rel="nofollow noreferrer">https://github.com/MichalDulemba/webdriverio</a></p>
  
  <p>Anybody can help?</p>
  
  <p>If it works I will create a gihub/docker hub repo for other people :)</p>
  
  <p>DOCKER COMPOSE:</p>
  
  <pre><code>version: '2'
  services:
      nightwatch:
          image: dulemba/nightwatch
          depends_on:
              - chrome
              - firefox
              - hub
          environment:
              - HUB_PORT_4444_TCP_ADDR=hub
              - HUB_PORT_4444_TCP_PORT=4444
          volumes:
              - /home/michal/Dokumenty/nw/nightwatch/app:/app
  
      hub:
          image: selenium/hub
          ports:
              - 4444:4444
  
      firefox:
          image: selenium/node-firefox-debug
          ports:
              - 5900
          environment:
              - HUB_PORT_4444_TCP_ADDR=hub
              - HUB_PORT_4444_TCP_PORT=4444
          depends_on:
              - hub
  
      chrome:
          image: selenium/node-chrome-debug
          ports:
              - 5900
          environment:
              - HUB_PORT_4444_TCP_ADDR=hub
              - HUB_PORT_4444_TCP_PORT=4444
          depends_on:
              - hub
  </code></pre>
  
  <p>NIGHTWATCH.JSON</p>
  
  <pre><code>{
    "src_folders" : ["tests"],
    "output_folder" : "reports",
    "custom_commands_path" : "",
    "custom_assertions_path" : "",
    "page_objects_path" : "",
    "globals_path" : "",
  
    "selenium" : {
      "start_process" : false,
      "server_path" : "/opt/selenium/selenium-server-standalone.jar",
      "log_path" : "",
      "host" : "127.0.0.1",
      "port" : 4444,
      "cli_args" : {
        "webdriver.chrome.driver" : "",
        "webdriver.gecko.driver" : "",
        "webdriver.edge.driver" : ""
      }
    },
  
    "test_settings" : {
      "default" : {
        "launch_url" : "http://localhost",
        "selenium_port"  : 4444,
        "selenium_host"  : "localhost",
        "silent": true,
        "screenshots" : {
          "enabled" : false,
          "path" : ""
        },
        "desiredCapabilities": {
          "browserName": "firefox",
          "marionette": true
        }
      },
  
      "chrome" : {
        "desiredCapabilities": {
          "browserName": "chrome"
        }
      },
  
      "edge" : {
        "desiredCapabilities": {
          "browserName": "MicrosoftEdge"
        }
      }
    }
  }
  </code></pre>