Cleanup heat/openstack/common

Remove jsonutils, strutils and timeutils modules.
They are not tracked in openstack-common.conf.
First two were not used anywhere, and single usage of timeutils is fixed
to use oslo.utils.

Change-Id: I368728e486bc7b05c0768df17123a0efad078efb
diff --git a/common/test.py b/common/test.py
index 7478f64..3de44f5 100644
--- a/common/test.py
+++ b/common/test.py
@@ -22,8 +22,8 @@
 import time
 
 from heatclient import exc as heat_exceptions
+from oslo.utils import timeutils
 
-from heat.openstack.common import timeutils
 from heat_integrationtests.common import clients
 from heat_integrationtests.common import config
 from heat_integrationtests.common import exceptions