Add image-diff plugin

Change-Id: I54be3f12f0df8891fbd4b1e909170e0f75580f1a
diff --git a/checkers.yaml b/checkers.yaml
index 05c7d20..0feddc7 100644
--- a/checkers.yaml
+++ b/checkers.yaml
@@ -176,6 +176,11 @@
     name: "Zuul Check Pipeline"
     description: "Run Zuul jobs on new patchsets"
 
+  - uuid: "zuul-check:plugins_image-diff"
+    repository: "plugins/image-diff"
+    name: "Zuul Check Pipeline"
+    description: "Run Zuul jobs on new patchsets"
+
   - uuid: "zuul-check:plugins_its-base"
     repository: "plugins/its-base"
     name: "Zuul Check Pipeline"
diff --git a/zuul/main.yaml b/zuul/main.yaml
index c6bcccf..8e60b7a 100644
--- a/zuul/main.yaml
+++ b/zuul/main.yaml
@@ -49,6 +49,7 @@
           - plugins/healthcheck
           - plugins/heartbeat
           - plugins/imagare
+          - plugins/image-diff
           - plugins/its-base
           - plugins/javamelody
           - plugins/lfs