#?? - ObjectUtils now uses proxy target class for Advised proxies.
#154 - Introduce XMLUnit to make sure we can build on Java 6 and 7.

Using XMLUnit's Diff to guard against minor changes in the default rendering of XML between Java 6 and 7.
#158 - HalEmbeddedBuilder now uses AopUtils.getTargetClass().

To correctly resolve the rel for a proxied class we need to build up relation types for, HalEmbeddedBuilder now uses Spring's AopUtils.getTargetClass(), which will use the object's getTargetClass() method in case it implements TargetClassAware.
Upgrade dependency versions