Add XML support to the volumes client.

Change-Id: Ie73b1a9cee293271cd7d5493a7c6e0dcb30cabe8
Signed-off-by: Matthew Treinish <treinish@linux.vnet.ibm.com>
diff --git a/tempest/manager.py b/tempest/manager.py
index 228c3b9..b13226d 100644
--- a/tempest/manager.py
+++ b/tempest/manager.py
@@ -48,7 +48,7 @@
 SecurityGroupsClient = security_groups_client.SecurityGroupsClient
 FloatingIPsClient = floating_ips_client.FloatingIPsClient
 KeyPairsClient = keypairs_client.KeyPairsClientJSON
-VolumesExtensionsClient = volumes_extensions_client.VolumesExtensionsClient
+VolumesExtensionsClient = volumes_extensions_client.VolumesExtensionsClientJSON
 VolumesClient = volumes_client.VolumesClient
 ConsoleOutputsClient = console_output_client.ConsoleOutputsClient