US52121 - Changes to WebDriverBrowser.open to match the interface method that it implements and return Event<T>

I'm somewhat anal about import organization (I try to follow [Google's Java Style Guide](https://google-styleguide.googlecode.com/svn/trunk/javaguide.html) as closely as possible). Inter-project imports should be grouped at the top, together (so all com.redhat.* together, basically).