title: Protractor gives "Unable to start a WebDriver session" error
body: <p>I already have started a server with <code>webdriver-manager start</code>, but I get this error when I try to run protractor:</p>
  
  <pre><code>Using the selenium server at http://127.0.0.1:4444/wd/hub
  [launcher] Running 1 instances of WebDriver
  ERROR - Unable to start a WebDriver session.
  
  C:\...\npm\node_modules\protractor\node_modules\selenium-webdriver\lib\atoms\error.js:113
    var template = new Error(this.message);
                   ^
  UnknownError: unknown error: cannot find Chrome binary
  </code></pre>
  
  <p>My config file looks like this:</p>
  
  <pre><code>exports.config = {
      specs: [
          'test/*.js'
      ],
  
      capabilities: {
          'browserName': 'chrome'
      },
      seleniumAddress: 'http://127.0.0.1:4444/wd/hub'
  
  };
  </code></pre>
  
  <p>I have also tried pointing to the binary in the capabilities object as well as adding chromeDriver and seleniumServerJar keys to no avail. Any ideas?</p>