SEBA-282 return 401 on permission error

Change-Id: Ica0c1d6b2aae5a8ed13123f2e5c0382e418b5433
diff --git a/src/web_server/main.py b/src/web_server/main.py
index 3e2cf8f..9a6c9b3 100644
--- a/src/web_server/main.py
+++ b/src/web_server/main.py
@@ -51,6 +51,8 @@
         request.setResponseCode(500)
         try:
             f = failure.getErrorMessage()
+            if f.startswith("XOSPermissionDenied"):
+                request.setResponseCode(401)
             log.info("[XOS-TOSCA] Error while loading TOSCA: \n\n", failure=f)
             return f
         except Exception: