increaase max attack id on older device

src/de/tudarmstadt/informatik/hostage/persistence/HostageDBOpenHelper.java

@@ -201,6 +201,7 @@ public class HostageDBOpenHelper extends SQLiteOpenHelper {
                 record.setLast_sync_timestamp(cursor.getLong(1));
                 record.setHighest_attack_id(cursor.getLong(2));
                 thisDevice = record;
+                thisDevice.setHighest_attack_id(attack_id-1);
                 cursor.close();
                 db.close();
                 // return record list