Remove CONF values from images clients

To move image clients to tempest-lib, this patch moves
CONF values from image clients to the client setting and classes
instantiate image clients.

Change-Id: I83b9466fc43bfcefd8d78c43f2c6e9dce4596d18
diff --git a/tempest/tests/common/test_service_clients.py b/tempest/tests/common/test_service_clients.py
index afe4abc..59d506c 100644
--- a/tempest/tests/common/test_service_clients.py
+++ b/tempest/tests/common/test_service_clients.py
@@ -55,6 +55,8 @@
 from tempest.services.identity.v3.json import policy_client
 from tempest.services.identity.v3.json import region_client
 from tempest.services.identity.v3.json import service_client
+from tempest.services.image.v1.json import image_client
+from tempest.services.image.v2.json import image_client as image_v2_client
 from tempest.services.messaging.json import messaging_client
 from tempest.services.network.json import network_client
 from tempest.services.object_storage import account_client
@@ -163,7 +165,9 @@
             identity_v3_identity_client.IdentityV3ClientJSON,
             policy_client.PolicyClientJSON,
             region_client.RegionClientJSON,
-            service_client.ServiceClientJSON
+            service_client.ServiceClientJSON,
+            image_client.ImageClientJSON,
+            image_v2_client.ImageClientV2JSON
         ]
 
         for client in test_clients: