Fix import group ordering in test_utils.py

Per the hacking guidelines the ordering for imports should be stdlib
first, followed by 3rd party imports, and last should the project
imports. However, test_utils.py did not adhere to this ordering. This
commit fixes the oversight.

Change-Id: I0fcc9d137706e841c2e22bd2af8ecd77135c78d2
diff --git a/tempest/scenario/utils.py b/tempest/scenario/utils.py
index 7b1a679..4c7b6d7 100644
--- a/tempest/scenario/utils.py
+++ b/tempest/scenario/utils.py
@@ -12,6 +12,12 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+
+import json
+import re
+import string
+import unicodedata
+
 import testscenarios
 import testtools
 
@@ -19,11 +25,6 @@
 from tempest.common.utils import misc
 from tempest import config
 
-import json
-import re
-import string
-import unicodedata
-
 CONF = config.CONF