fix name in pull-etcd-image

Change-Id: Ifd0e54460ef5b771204464fd9373446b1ba7e682
diff --git a/etcd/server/service.sls b/etcd/server/service.sls
index 1524715..34f35b3 100644
--- a/etcd/server/service.sls
+++ b/etcd/server/service.sls
@@ -63,7 +63,7 @@
 
 pull-etcd-image:
   dockerng.image_present:
-    - image: {{ server.get('image', 'quay.io/coreos/etcd:latest') }}
+    - name: {{ server.get('image', 'quay.io/coreos/etcd:latest') }}
 
 copy-etcd-binaries:
   dockerng.running: