#9: added interface for ExtensiblePersistentObject 

Task-Url: http://github.com/mgatz/sunrise/issues/issue/9
#9: added interface for extensible objects, added LocaleHelper class
including unit tests

Task-Url: http://github.com/mgatz/sunrise/issues/issue/9
#9: Implement possibility to extend pojo objects with dynamic named
attributes
FINISHED

Task-Url: http://github.com/mgatz/sunrise/issues/issue/9