Convert all service clients to global CONF object

This commit takes the rest client and all subclass(all the service
clients) and converts all uses of config to the global CONF object.

Partially implements bp config-cleanup

Change-Id: I09525af4f1b308b91d45b7bbea05e0f734ea485c
diff --git a/tempest/services/compute/v3/json/servers_client.py b/tempest/services/compute/v3/json/servers_client.py
index ef282fa..aa8c95a 100644
--- a/tempest/services/compute/v3/json/servers_client.py
+++ b/tempest/services/compute/v3/json/servers_client.py
@@ -21,17 +21,20 @@
 
 from tempest.common.rest_client import RestClient
 from tempest.common import waiters
+from tempest import config
 from tempest import exceptions
 
+CONF = config.CONF
+
 
 class ServersV3ClientJSON(RestClient):
 
-    def __init__(self, config, username, password, auth_url,
+    def __init__(self, username, password, auth_url,
                  tenant_name=None, auth_version='v2'):
-        super(ServersV3ClientJSON, self).__init__(config, username, password,
+        super(ServersV3ClientJSON, self).__init__(username, password,
                                                   auth_url, tenant_name,
                                                   auth_version=auth_version)
-        self.service = self.config.compute.catalog_v3_type
+        self.service = CONF.compute.catalog_v3_type
 
     def create_server(self, name, image_ref, flavor_ref, **kwargs):
         """