Added overload about checking element is visible

Overload accepting a jQuery selector
Merge pull request #47 from Gwayaboy/dev

Thanks, Franck. It's a useful overload. Wish we could sort out the jQueryBy inheritance though...
Update Selenium to 2.33.0
Merge pull request #57 from joshka/selenium-2.33

Update Selenium to 2.33.0