Moved usergroups to the new put mechanism

ref #39

src/controllers/UserGroupController.ts

@@ -73,7 +73,7 @@ export class UserGroupController {
 			throw new UserGroupIdsNotMatchingError();
 		}
 
-		await this.userGroupsRepository.update(oldUserGroup, userGroup);
+		await this.userGroupsRepository.save(userGroup);
 		return userGroup;
 	}