Drop keystone dedicated ports

Those historic references to port 5000 and 35357 aren't being used
anymore for some time, so let us drop them.

Clean up some python2/3 wording along the way.

No longer mention Identity API v2, which is also a thing of the past.

Change-Id: Iafff097eee082f24ea2ae27ad038ad115aa36c61
diff --git a/openrc b/openrc
index beeaebe..28f388b 100644
--- a/openrc
+++ b/openrc
@@ -86,7 +86,7 @@
 #
 
 # If you don't have a working .stackenv, this is the backup position
-KEYSTONE_BACKUP=$SERVICE_PROTOCOL://$SERVICE_HOST:5000
+KEYSTONE_BACKUP=$SERVICE_PROTOCOL://$SERVICE_HOST/identity
 KEYSTONE_SERVICE_URI=${KEYSTONE_SERVICE_URI:-$KEYSTONE_BACKUP}
 
 export OS_AUTH_URL=${OS_AUTH_URL:-$KEYSTONE_SERVICE_URI}