Removed RestClientXML class

After unifying RestClient class to handle both container
types - json and xml, class RestClientXML becomes redundant.

Change-Id: I1bcf5e4df130b8eee26d0abcf1741ba3ea8f3d00
Partially-implements: bp refactor-rest-client
diff --git a/tempest/services/volume/xml/volumes_client.py b/tempest/services/volume/xml/volumes_client.py
index 94c1ff6..aef1e3c 100644
--- a/tempest/services/volume/xml/volumes_client.py
+++ b/tempest/services/volume/xml/volumes_client.py
@@ -19,7 +19,7 @@
 from lxml import etree
 from xml.sax.saxutils import escape
 
-from tempest.common.rest_client import RestClientXML
+from tempest.common import rest_client
 from tempest import config
 from tempest import exceptions
 from tempest.services.compute.xml.common import Document
@@ -31,10 +31,11 @@
 CONF = config.CONF
 
 
-class VolumesClientXML(RestClientXML):
+class VolumesClientXML(rest_client.RestClient):
     """
     Client class to send CRUD Volume API requests to a Cinder endpoint
     """
+    TYPE = "xml"
 
     def __init__(self, auth_provider):
         super(VolumesClientXML, self).__init__(auth_provider)