Use service_has_permission decorator on inbox

This proves that the decorator works, because the inbox code is already
tested:
bad1e69cc3/tests/app/main/views/test_dashboard.py (L353-L367)

app/utils.py

@@ -83,7 +83,9 @@ def user_has_permissions(*permissions, **permission_kwargs):
 
 
 def service_has_permission(permission):
+
     from app import current_service
+
     def wrap(func):
         @wraps(func)
         def wrap_func(*args, **kwargs):