Prepare for enabling H302 rule(services/compute/json)

Currently H302 rule is ignored by tox. However, this rule should
be enabled. This patch partially fixes this problem to prepare for
H302 rule.

Change-Id: I93204fb215b54b8a304224b249320428870dedde
diff --git a/tempest/services/compute/json/services_client.py b/tempest/services/compute/json/services_client.py
index 8380dc2..1ab25ec 100644
--- a/tempest/services/compute/json/services_client.py
+++ b/tempest/services/compute/json/services_client.py
@@ -17,13 +17,13 @@
 import json
 import urllib
 
-from tempest.common.rest_client import RestClient
+from tempest.common import rest_client
 from tempest import config
 
 CONF = config.CONF
 
 
-class ServicesClientJSON(RestClient):
+class ServicesClientJSON(rest_client.RestClient):
 
     def __init__(self, auth_provider):
         super(ServicesClientJSON, self).__init__(auth_provider)