Update base ubuntu image to 16.04.5

Change-Id: Ie60dd5fc057ac5174a89933c9fafd1a8996e85e5
Signed-off-by: Michael Marchetti <mmarchetti@sandvine.com>

packer/ubuntu1604-juju.json

@@ -72,11 +72,11 @@
       "headless": true,
       "http_directory": "http",
       "iso_urls": [
-        "iso/ubuntu-16.04.4-server-amd64.iso",
-        "http://releases.ubuntu.com/16.04/ubuntu-16.04.4-server-amd64.iso"
+        "iso/ubuntu-16.04.5-server-amd64.iso",
+        "http://releases.ubuntu.com/16.04/ubuntu-16.04.5-server-amd64.iso"
       ],
       "iso_checksum_type": "sha256",
-      "iso_checksum": "0a03608988cfd2e50567990dc8be96fb3c501e198e2e6efcb846d89efc7b89f2",
+      "iso_checksum": "c94de1cc2e10160f325eb54638a5b5aa38f181d60ee33dae9578d96d932ee5f8",
       "ssh_username": "vagrant",
       "ssh_password": "vagrant",
       "ssh_port": 22,