Do not log errors in the ErrorHandler

This change is to suppress excessive logging for exceptions that are captured and handled correctly downstream. Specifically, we're following the [conventions suggested in the documentation](http://finatra.info/docs/index.html#routing) by using an error handler to respond to certain requests a 404 NOT FOUND. Because of this `log.error()` in this method, a full stacktrace is printed to the logs with the message "Internal Server Error" even though it's not really an internal error.