title: Passing command line arguments to nightwatch.runner
body: <p>I have a test setup that accepts dynamic values for predefined options (e.g: --foo="bar", --foo="car", etc) which works perfectly when run from the command line. </p>
  
  <p>This works:</p>
  
  <p><code>./node_modules/nightwatch/bin/nightwatch ./tests/test.js --env "production" --foo="bar"</code></p>
  
  <p>However, I want to call the test from inside a node app, but can't quite seem to get the extra parameters passed into my test. My test initializes correctly, but then fails because I can't get any of the extra params.</p>
  
  <pre><code>try {
      const nightwatch = require('nightwatch');
  
      const argv = {
          config: 'nightwatch.json',
          test: 'test.js',
          env: 'default',
          foo: 'bar',
      };
  
      const done = function() {
          console.log('nightwatch complete');
      }; // your callback function
  
      const settings = {};
  
      nightwatch.runner(argv, done, settings);
  
  } catch (error) {
      console.log('Exception:' + error.message);
  }
  </code></pre>
  
  <p>There seems to be absolutely no documentation for nightwatch.runner or nightwatch.cli so any help you can provide would be greatly appreciated.</p>