Fix bug 1255: returning UNPROCESSABLE_ENTITY when quota exceeded

When quota exceeded for vnfds, nsds, ns_instances topics, NBI
should return UNPROCESSABLE_ENTITY instead of UNAUTHORIZED

Change-Id: I0a8f4dc1df844e1027ff8234f101b82baa0bcee8
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>
diff --git a/osm_nbi/base_topic.py b/osm_nbi/base_topic.py
index 9572409..c67ec76 100644
--- a/osm_nbi/base_topic.py
+++ b/osm_nbi/base_topic.py
@@ -147,7 +147,7 @@
             if count >= quota:
                 name = proj["name"]
                 raise ValidationError("quota ({}={}) exceeded for project {} ({})".format(quota_name, quota, name, pid),
-                                      http_code=HTTPStatus.UNAUTHORIZED)
+                                      http_code=HTTPStatus.UNPROCESSABLE_ENTITY)
 
     def _validate_input_new(self, input, force=False):
         """