Revert "Move default Keystone API version to v3"

It seems like the fallout from this was not well sorted.
A lot of things aren't working, and there is still vestigial
v2 bits left behind.

This should have come with a much greater warning and some
spot checking of additional services working with this.

This reverts commit b162a1d58cdecfb32847b59bd341e06c26efb1ed.

Change-Id: Ia792b23119c00089542ba08879dca1c29dc80945
diff --git a/lib/nova_plugins/hypervisor-ironic b/lib/nova_plugins/hypervisor-ironic
index 2aa9b12..c6ed85d 100644
--- a/lib/nova_plugins/hypervisor-ironic
+++ b/lib/nova_plugins/hypervisor-ironic
@@ -47,7 +47,7 @@
     # ironic section
     iniset $NOVA_CONF ironic admin_username admin
     iniset $NOVA_CONF ironic admin_password $ADMIN_PASSWORD
-    iniset $NOVA_CONF ironic admin_url $KEYSTONE_AUTH_URI/v3
+    iniset $NOVA_CONF ironic admin_url $KEYSTONE_AUTH_URI/v2.0
     iniset $NOVA_CONF ironic admin_tenant_name demo
     iniset $NOVA_CONF ironic api_endpoint $IRONIC_SERVICE_PROTOCOL://$IRONIC_HOSTPORT/v1
 }