Fix Bug 917: Revoke NBI's Auth token once user is deleted

Change-Id: I1060af8065d95beab5b9dc3be27abc8e3601f3e8
Signed-off-by: delacruzramo <pedro.delacruzramos@altran.com>
diff --git a/osm_nbi/nbi.py b/osm_nbi/nbi.py
index ac30a37..b7a2c13 100644
--- a/osm_nbi/nbi.py
+++ b/osm_nbi/nbi.py
@@ -482,8 +482,8 @@
 
     def __init__(self):
         self.instance += 1
-        self.engine = Engine()
         self.authenticator = Authenticator(valid_url_methods, valid_query_string)
+        self.engine = Engine(self.authenticator.tokens_cache)
 
     def _format_in(self, kwargs):
         try: