Policy.json should be defined by user

User can override and add values to policy.json by creating flat
key-value structure under glance:server:policy.

Change-Id: I4db6b17ab1ff925aa20cd3565417a4b35ed4561e
diff --git a/metadata.yml b/metadata.yml
index 3f3d02b..ba720bc 100644
--- a/metadata.yml
+++ b/metadata.yml
@@ -1,3 +1,6 @@
 name: "glance"
 version: "2016.4.1"
 source: "https://github.com/openstack/salt-formula-glance"
+dependencies:
+  - name: keystone
+    source: "https://github.com/salt-formulas/salt-formula-keystone"