Adding setTimeouts to Selenium2 driver

This change allows client code to set the three WebDriver timeouts in miliseconds:

    $driver->setTimeouts([
      'page' => 1000,
      'implicit' => 2000,
      'script' => 3000
    )];
Merge pull request #98 from ciaranmcnulty/timeouts-config

Ability to configure WebDriver timeouts