update defaults

  * Add static files list, for offline build
  * Unhardcode mcp_static_images_url
  * Unhardcode salt_control_*_image

Change-Id: Ia774d16a0f34362535d4f91d3add47b8ecebf7c1
Prod-related: PROD-26662 (PROD:26662)
diff --git a/defaults/salt/init.yml b/defaults/salt/init.yml
index 3193878..2e19089 100644
--- a/defaults/salt/init.yml
+++ b/defaults/salt/init.yml
@@ -44,3 +44,7 @@
     salt_control_size_image_layout_stacklight_log: ${_param:salt_control_size_image_layout_default}
     salt_control_size_image_layout_stacklight_server: ${_param:salt_control_size_image_layout_default}
     salt_control_size_image_layout_stacklight_telemetry: ${_param:salt_control_size_image_layout_default}
+
+    salt_control_trusty_image: ${_param:mcp_static_images_url}/ubuntu-14-04-x64-mcp${_param:mcp_version}.qcow2
+    salt_control_xenial_image: ${_param:mcp_static_images_url}/ubuntu-16-04-x64-mcp${_param:mcp_version}.qcow2
+