Manage policy files in Horizon

Manage policy files in Horizon conf directory, either dynamically
from Salt Mine or statically from Horizon formula directory.
diff --git a/metadata/service/server/single.yml b/metadata/service/server/single.yml
index 9eb974a..99d165b 100644
--- a/metadata/service/server/single.yml
+++ b/metadata/service/server/single.yml
@@ -39,3 +39,33 @@
         host: ${_param:horizon_identity_host}
         encryption: ${_param:horizon_identity_encryption}
         endpoint_type: ${_param:horizon_identity_endpoint_type}
+      policy:
+        identity:
+          source: file
+          name: keystone_policy.json
+          enabled: true
+        compute:
+          source: file
+          name: nova_policy.json
+          enabled: true
+        network:
+          source: file
+          name: neutron_policy.json
+          enabled: true
+        image:
+          source: file
+          name: glance_policy.json
+          enabled: true
+        volume:
+          source: file
+          name: cinder_policy.json
+          enabled: true
+        telemetry:
+          source: file
+          name: ceilometer_policy.json
+          enabled: true
+        orchestration:
+          source: file
+          name: heat_policy.json
+          enabled: true
+