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/barbican/server/cluster.yml b/barbican/server/cluster.yml
index 5b5bc5e..ed45b47 100644
--- a/barbican/server/cluster.yml
+++ b/barbican/server/cluster.yml
@@ -1,3 +1,10 @@
 classes:
 - service.barbican.server.cluster
-- system.haproxy.proxy.listen.openstack.barbican
\ No newline at end of file
+- system.haproxy.proxy.listen.openstack.barbican
+parameters:
+  _param:
+    cluster_internal_protocol: 'http'
+  barbican:
+    server:
+      identity:
+        protocol: ${_param:cluster_internal_protocol}