Fixed ERRAI-529: IoC generates invalid code for some usages of generics
fix to ERRAI-536
Fixed ERRAI-537: Jackson marshalling with Enums as map keys
Refactoring and improved fix for ERRAI-537 (MapMarshaller shouldn't introduce dep. to gwt-user)

Also configured test entity to use @JsonSerialize(using=ToStringSerializer.class) to marshall longs as strings which should always be the case when parsing JSON in the browser.