Added wrapper method for rollback

Signed-off-by: Jim Martens <github@2martens.de>

07/src/de/dis2017/data/db/ORM.java

@@ -39,6 +39,14 @@ public class ORM {
         }
     }
     
+    public void rollback() {
+        try {
+            _connection.rollback();
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+    }
+    
     public List<Article> getArticles()
     {
         List<Article> articles = new ArrayList<>();