Switch all uses of json to oslo_serialization

This commit migrates all the usage of the json library to use jsonutils
from oslo_serialization. On python 3 httplib2 returns a bytes type for
the response body however all the methods in the json library are
expecting str types. We could switch all the uses of json.loads to
encode the input prior to calling json.loads however oslo_serialization
has baked in all dual python version edge conditions around this into
a call compatible lib which is much cleaner.

Change-Id: Icee30fb74db128c77b2c0c27e68b5801bd138cd5
diff --git a/tempest/scenario/utils.py b/tempest/scenario/utils.py
index cd9d925..b1246d2 100644
--- a/tempest/scenario/utils.py
+++ b/tempest/scenario/utils.py
@@ -13,11 +13,11 @@
 #    under the License.
 
 
-import json
 import re
 import string
 import unicodedata
 
+from oslo_serialization import jsonutils as json
 from tempest_lib.common.utils import misc
 import testscenarios
 import testtools