Centralize setting internal_protocol

Internal Openstack APIs may be encrypted with https. This patch
centralize setting internal API protocol among services by
setting one of depending if cluster or single models are used:
  cluster_internal_protocol: 'https'
  internal_protocol: 'https'

Change-Id: I2baff79cd5851678559d7de47460fdd2031f70ee
diff --git a/neutron/control/single.yml b/neutron/control/single.yml
index 7f02325..067b4df 100644
--- a/neutron/control/single.yml
+++ b/neutron/control/single.yml
@@ -2,6 +2,8 @@
 - service.neutron.control.single
 - system.galera.server.database.neutron
 parameters:
+  _param:
+    internal_protocol: 'http'
   linux:
     system:
       package:
@@ -12,3 +14,5 @@
     server:
       database:
         host: ${_param:single_address}
+      identity:
+        protocol: ${_param:internal_protocol}