frontend CHANGE refactor configuration view

provide new service to handle tree from several components
diff --git a/frontend/config/modifications.service.ts b/frontend/config/modifications.service.ts
index a0de997..14a3b05 100644
--- a/frontend/config/modifications.service.ts
+++ b/frontend/config/modifications.service.ts
@@ -4,7 +4,7 @@
 import { SessionsService } from './sessions.service';
 
 @Injectable()
-export class ModificationsService{
+export class ModificationsService {
 
     constructor(private sessionsService: SessionsService) {}