Resolve "Die Statistiken sollten auch in ElasticSearch hinterlegt werden."

Related to #384 (closed)

src/main/java/at/ac/uibk/gitsearch/domain/vocabulary/VocabularyItem.java

@@ -5,10 +5,6 @@ import java.util.Arrays;
 import java.util.UUID;
 import java.util.stream.Collectors;
 
-// @JsonTypeInfo(use = Id.DEDUCTION)
-// @JsonSubTypes(
-//    { @JsonSubTypes.Type(DifficultyItem.class), @JsonSubTypes.Type(ProgrammingLanguageItem.class), @JsonSubTypes.Type(KeywordItem.class) }
-// )
 public class VocabularyItem {
 
     private String createdOn;