Bugfix: Print the WebDriverException, when an element doesn't exists

I found a bug when you grab an element which doesn't exists. For this case no try catch block around the Exception, so you can't use the $e->getMessage().

Stack Trace was:

    Fatal error: Call to a member function getMessage() on a non-object in ...\vendor\instaclick\php-webdriver\lib\WebDriver\Container.php on line 89