Fix packer node

Update packer/vars/centos-7 build node to
an available one.

Change-Id: I9edda4165c484c5d9ae0b6ca1316cb95d8bbb3b9
Issue-ID: CIMAN-33
Signed-off-by: Jessica Wagantall <jwagantall@linuxfoundation.org>
diff --git a/packer/vars/centos-7.json b/packer/vars/centos-7.json
index 366202c..3bae793 100644
--- a/packer/vars/centos-7.json
+++ b/packer/vars/centos-7.json
@@ -1,5 +1,5 @@
 {
-  "base_image": "CentOS 7.1611 (2017-01-30) - LF upload",
+  "base_image": "ZZCI - CentOS 7 - builder - 20180328-1726",
   "ssh_user": "centos",
   "distro": "CentOS 7",
   "cloud_user_data": "provision/rh-user_data.sh"