Restore heat tests running with admin user, demo tenant

heat currently needs an admin user so that stacks can create users
however the tests need the demo tenant so that the neutron
private network is the default.

There is now a comment which explains the situation so that this
isn't changed again.

Change-Id: Ifd91d2a5af40e9697b51c3d48b13220d358cbcd8
Closes-Bug: #1281768
diff --git a/tempest/clients.py b/tempest/clients.py
index c262a20..d0eb1cc 100644
--- a/tempest/clients.py
+++ b/tempest/clients.py
@@ -439,8 +439,12 @@
     """
     def __init__(self, interface='json', service=None):
         base = super(OrchestrationManager, self)
+        # heat currently needs an admin user so that stacks can create users
+        # however the tests need the demo tenant so that the neutron
+        # private network is the default. DO NOT change this auth combination
+        # until heat can run with the demo user.
         base.__init__(CONF.identity.admin_username,
                       CONF.identity.admin_password,
-                      CONF.identity.admin_tenant_name,
+                      CONF.identity.tenant_name,
                       interface=interface,
                       service=service)