Remove all CONF values from RestClient

To moving RestClient to tempest-lib, this patch moves all CONF values
from RestClient to service clients. This patch adds TempestRestClient
which passes common CONF values for Tempest own values.

Change-Id: I3434061fd19de741e36b13bd3c458cf49fdfe783
diff --git a/tempest/services/image/v1/json/image_client.py b/tempest/services/image/v1/json/image_client.py
index 0d35ef5..06ba4f7 100644
--- a/tempest/services/image/v1/json/image_client.py
+++ b/tempest/services/image/v1/json/image_client.py
@@ -22,6 +22,7 @@
 
 from tempest.common import glance_http
 from tempest.common import rest_client
+from tempest.common import service_client
 from tempest.common.utils import misc as misc_utils
 from tempest import config
 from tempest import exceptions
@@ -32,7 +33,7 @@
 LOG = logging.getLogger(__name__)
 
 
-class ImageClientJSON(rest_client.RestClient):
+class ImageClientJSON(service_client.ServiceClient):
 
     def __init__(self, auth_provider):
         super(ImageClientJSON, self).__init__(