/**
  * @param DesiredCapabilities $desiredCapabilities
  * @param String $host
  * @param Integer $port
  */
 public function __construct(DesiredCapabilities $desiredCapabilities = null, $host = "http://localhost", $port = 4444)
 {
     $this->_hubUrl = "{$host}:{$port}/wd/hub";
     isset($desiredCapabilities) ?: ($desiredCapabilities = new DesiredCapabilities("firefox"));
     $this->_httpClient = HttpFactory::getClient($this->_environment);
     $this->startSession($desiredCapabilities);
 }