READY: Allow web elements to be passed to clickable

According to [the ExpectedCondition docs](http://selenium.googlecode.com/git/docs/api/java/org/openqa/selenium/support/ui/ExpectedConditions.html), elementToBeClickable can take a By or a WebElement. In most cases, I've already got a web element and want to check it's state, so it would be nice to just pass the element.