Adding hippie-oss synchronizer to buildable images

Change-Id: Ia7d5706c13efd8a18047a630f01587a35fe42fd1
diff --git a/docker_images.yml b/docker_images.yml
index 866b018..dcb09ab 100644
--- a/docker_images.yml
+++ b/docker_images.yml
@@ -257,6 +257,10 @@
     path: "xos/synchronizer"
     dockerfile: "Dockerfile.synchronizer"
 
+  - name: xosproject/hippie-oss-synchronizer
+    repo: hippie-oss
+    dockerfile: "Dockerfile.synchronizer"
+
   - name: xosproject/xos-api-tester
     repo: cord-tester
     path: "src/test/cord-api"