Revert https://review.opencontrail.org/#/c/4683/ as it breaks discovery

Change-Id: I4a213c8220919414a21db0c299cce62a2f5de581

src/discovery/disc_server.py

@@ -329,7 +329,7 @@ def service_expired(self, entry, include_color=False, include_down=True):
 
     # decorator to catch DB error
     def db_error_handler(func):
-        def error_handler(self, *args, **kwargs):
+        def error_handler(*args, **kwargs):
             try:
                 return func(*args,**kwargs)
             except disc_exceptions.ServiceUnavailable: