copy etcd from images

when server.image is set then binary is copied from docker image

Change-Id: I59c220deabfdf861613f16cf757ba0da44976a9c
diff --git a/tests/pillar/cluster.sls b/tests/pillar/cluster.sls
index 730b768..a91825f 100644
--- a/tests/pillar/cluster.sls
+++ b/tests/pillar/cluster.sls
@@ -1,5 +1,6 @@
 etcd:
   server:
+    image: quay.io/coreos/etcd:latest
     enabled: true
     bind:
       host: 10.0.175.101
@@ -13,4 +14,4 @@
       port: 4001
     - host: 10.0.175.103
       name: etcd03
-      port: 4001
\ No newline at end of file
+      port: 4001