CORD-2878 build the xos-core image

Change-Id: Ie59b4e45810c44e3b332fb74a60290a150747d60
diff --git a/docker_images.yml b/docker_images.yml
index d2b3447..75c7351 100644
--- a/docker_images.yml
+++ b/docker_images.yml
@@ -62,6 +62,12 @@
     repo: xos
     path: "containers/postgresql"
 
+  - name: xosproject/xos-core
+    repo: xos
+    path: "containers/xos"
+    dockerfile: "Dockerfile.xos-core"
+    context: "../.."
+
   - name: xosproject/xos
     repo: xos
     path: "containers/xos"