Allow keystone endpoint_type interpolation for reclass models

- Add 'endpoint_type' identity parameter
- Set 'endpoint_type: internalURL' as a default parameter for
  'service' reclass model (/metadata/)

Change-Id: I9626989e2e13e6acd2f83b020709913abc841da3
diff --git a/metadata/service/server/single.yml b/metadata/service/server/single.yml
index f49b9d6..fe119a4 100644
--- a/metadata/service/server/single.yml
+++ b/metadata/service/server/single.yml
@@ -8,6 +8,7 @@
     horizon_identity_host: localhost
     horizon_identity_version: 3
     horizon_identity_encryption: none
+    horizon_identity_endpoint_type: internalURL
   horizon:
     server:
       enabled: true
@@ -34,3 +35,4 @@
         host: ${_param:horizon_identity_host}
         encryption: ${_param:horizon_identity_encryption}
         api_version: ${_param:horizon_identity_version}
+        endpoint_type: ${_param:horizon_identity_endpoint_type}