tempest: import ImagesClient as ImagesClientV2

This commit [1] renamed ImagesClientV2 to ImagesClient so Ceilometer
Tempest tests do not work anymore.

[1] https://github.com/openstack/tempest/commit/2fea405bd6ea8674c8daaf8ebb788ae33d52c976

Change-Id: Ie1d430982174fab11693ded9e9c5574d00151342
diff --git a/ceilometer/tests/tempest/service/client.py b/ceilometer/tests/tempest/service/client.py
index 81d67d8..5c92f7e 100644
--- a/ceilometer/tests/tempest/service/client.py
+++ b/ceilometer/tests/tempest/service/client.py
@@ -24,7 +24,8 @@
 from tempest.lib.services.compute.servers_client import ServersClient
 from tempest import manager
 from tempest.services.image.v1.json.images_client import ImagesClient
-from tempest.services.image.v2.json.images_client import ImagesClientV2
+from tempest.services.image.v2.json.images_client import \
+    ImagesClient as ImagesClientV2
 from tempest.services.object_storage.container_client import ContainerClient
 from tempest.services.object_storage.object_client import ObjectClient