Fixes handling of arrays in XML to JSON conversion

The xml to json method in compute/xml/common.py has
an option to specify which XML elements shall be translated
to a list rather than a dict.
The current implementation though applies only for the
first level of elements and it's not passed down to
children elements.

Closes-Bug: #1267867
Change-Id: I70f6b95fbeac2a9e28e935e506ba43d183690994
diff --git a/tempest/services/compute/xml/common.py b/tempest/services/compute/xml/common.py
index d2a18a1..76ad1aa 100644
--- a/tempest/services/compute/xml/common.py
+++ b/tempest/services/compute/xml/common.py
@@ -124,9 +124,9 @@
         if tag.startswith("{"):
             ns, tag = tag.split("}", 1)
         if plurals is not None and tag in plurals:
-                json[tag] = parse_array(child)
+                json[tag] = parse_array(child, plurals)
         else:
-            json[tag] = xml_to_json(child)
+            json[tag] = xml_to_json(child, plurals)
     return json