* Instructs Spring MVC on how to parse and print elements of type 'PetType'.
* Starting from Spring 3.0, Formatters have come as an improvement in comparison to legacy PropertyEditors.
* See the following links for more details:
* - The Spring ref doc: {@linktourl http://static.springsource.org/spring/docs/current/spring-framework-reference/html/validation.html#format-Formatter-SPI
* - The Spring ref doc: http://static.springsource.org/spring/docs/current/spring-framework-reference/html/validation.html#format-Formatter-SPI
* - A nice blog entry from Gordon Dickens: http://gordondickens.com/wordpress/2010/09/30/using-spring-3-0-custom-type-converter/
*
* Also see how the bean 'conversionService' has been declared inside /WEB-INF/mvc-core-config.xml