selenium-webdriver: Added selenium testing & executors modules

See example here
https://code.google.com/p/selenium/wiki/WebDriverJs#Writing_Tests

Docs here http://selenium.googlecode.com/git/docs/api/javascript/module_selenium-webdriver_executors.html and here http://selenium.googlecode.com/git/docs/api/javascript/module_selenium-webdriver_testing.html