Do not implement methodmissing to avoid hijacking controller methods

I was mistaken that the root problem was just throwing an exception in methodmissing.  Further testing shows that it is still hijacking methods, now silently (making them return null), which is arguably much worse.  I've taken a much simpler approach that avoids methodmissing altogether to eliminate the problem and rather adds a single 'isInCountry(String countryCode)' dynamic method to all controllers.   Documentation updated appropriately.