Set the image version for the 0.0.0-alpha.4 release. (#635)

Author: Robert Bailey

config/default/manager_image_patch.yaml

@@ -7,5 +7,5 @@ spec:
   template:
     spec:
       containers:
-      - image: gcr.io/k8s-cluster-api/cluster-api-controller:latest
+      - image: gcr.io/k8s-cluster-api/cluster-api-controller:0.0.0-alpha.4
         name: manager