replace deprecated heat command with OSC

Integration gate test complains:

    WARNING (shell) "heat stack-show" is deprecated, please use
    "openstack stack show" instead

Change-Id: I2af4315a46bceb62cd5fe8afcd4b3e3ee8b5420d
diff --git a/ceilometer/tests/integration/hooks/post_test_hook.sh b/ceilometer/tests/integration/hooks/post_test_hook.sh
index 182806a..fbc69a7 100755
--- a/ceilometer/tests/integration/hooks/post_test_hook.sh
+++ b/ceilometer/tests/integration/hooks/post_test_hook.sh
@@ -59,7 +59,7 @@
 if [ $EXIT_CODE -ne 0 ] ; then
     set +x
     echo "* Heat stack:"
-    heat stack-show integration_test
+    openstack stack show integration_test
     echo "* Alarm list:"
     ceilometer alarm-list
     echo "* Nova instance list:"