Fix auth issue when accessing root path "/"

Now when access the root path of Zaqar service, for example:
curl GET http://127.0.0.1:8888/, user will see 401 error. Which
will cause some front end proxy(like HAProxy) complain. This
patch fixes the issue.

Closes-Bug: #1569474

Change-Id: I92c98495bf26277cd4c8c1d019c54698cace4bbd

zaqar/transport/auth.py

@@ -32,6 +32,11 @@ class SignedHeadersAuth(object):
 
     def __call__(self, environ, start_response):
         path = environ.get('PATH_INFO')
+        # NOTE(flwang): The root path of Zaqar service shouldn't require any
+        # auth.
+        if path == '/':
+            return self._app(environ, start_response)
+
         signature = environ.get('HTTP_URL_SIGNATURE')
 
         if signature is None or path.startswith('/v1'):