I am trying to setup Nightwatch so that I do not have to use Selenium and instead point directly to an instance of Chrome on Linux, but I seem to be unable to connect to the chromedriver instance.

nightwatch.json
---------------

```
{
  "src_folders" : ["tests"],
  "output_folder" : "reports",
  "custom_commands_path" : "",
  "custom_assertions_path" : "",
  "page_objects_path" : "",
  "globals_path" : "globals.js",

  "selenium" : {
    "start_process" : false,
    "cli_args" : {
      "webdriver.chrome.driver" : "./chromedriver"
    }
  },

  "test_settings" : {
    "default" : {
      "selenium_port"  : 9515,
      "selenium_host"  : "127.0.0.1",
      "silent": true,
      "screenshots" : {
        "enabled" : false,
        "path" : ""
      },
      "desiredCapabilities": {
        "browserName": "chrome",
    "acceptSslCerts": true
      }
    }
  }
}

```

After attempting to run a simple test suite, I get the following error

```
 ~/scripts/TestNightwatch$ nightwatch 

 [Test] Test Suite
 =====================

 Running:  Demo test Google Error processing the server response:  
 unknown command: wd/hub/session

 Error retrieving a new session from the selenium server

 Connection refused! Is selenium server started? { value: -1, error:
 'Unexpected token u in JSON at position 0' }

```

Have I not configured nightwatch properly to connect to Chrome? Am I missing any pieces of the puzzle?

Thanks in advance!

globals.js
----------

```
var chromedriver = require('chromedriver');

module.exports = {
  before : function(done) {
    chromedriver.start();

    done();
  },

  after : function(done) {
    chromedriver.stop();

    done();
  }
}

```