Merge pull request #579 from sandermarechal/default-locale

Properly handle translation updates in default locale
- translatable entity has no getObject method
- correction, translated object MAY have an getObject method
clean up code, throws an exception if translation entity does not extend either AbstractTranslation or AbstractPersonalTranslation
Implemented proposed code changes
merging changes from trans-object branch
improved emtpy-check before deciding whether or not an update is needed
Merge branch 'empty-translation' into prezent