Define v1 images_client as library

Image v1 API's images_client has good interfaces now,
then this patch makes the client as a library.

Partially implements blueprint consistent-service-method-names

Change-Id: I8a0346e5526bfb83e54e0184bbc34ad5195203c3
diff --git a/tempest/common/waiters.py b/tempest/common/waiters.py
index d8dad69..e083167 100644
--- a/tempest/common/waiters.py
+++ b/tempest/common/waiters.py
@@ -20,7 +20,7 @@
 from tempest import exceptions
 from tempest.lib.common.utils import misc as misc_utils
 from tempest.lib import exceptions as lib_exc
-from tempest.services.image.v1.json import images_client as images_v1_client
+from tempest.lib.services.image.v1 import images_client as images_v1_client
 
 CONF = config.CONF
 LOG = logging.getLogger(__name__)