Add example of loading cell from a nib

Resolves #2. Thanks to @mbogh for helping put this together!

There are still 2 outstanding issues, they seem like Apple bugs at this point:
1. Cells loaded from a nib do not size correctly in iOS 8 when the table view width is not 320pts (e.g. landscape iPhone, any iPad). (Programmatically loaded cells work fine.)
2. Changing the Dynamic Type slider while the app is running does not fire the UIContentSizeCategoryDidChangeNotification, meaning the app does not respond by updating its UI until it is killed and launched again.