Handle no status from ansible uri module

There are apparently cases where the ansible uri module won't have a
status item in its result dict. Check that status is there before
comparing against its value when doing network sanity checks.

Without this the following issue can occur:

2017-04-17 03:33:34.536 | localhost | FAILED! => {
    "failed": true,
    "msg": "The conditional check 'uri_result['status'] == 200' failed. The error was: error while evaluating conditional (uri_result['status'] == 200): 'dict object' has no attribute 'status'"
}

Change-Id: I5c848bfbb955b7201abcef71c2cbba2ec0644b1a

playbooks/roles/network_sanity_check/tasks/http_check.yaml

@@ -1,5 +1,6 @@
 - name: Perform HTTP check
   uri: url={{ url }}
   register: uri_result
-  until: uri_result['status'] == 200
+  until: ('status' in uri_result and uri_result['status'] == 200)
+  changed_when: False
   retries: "{{ HTTP_TIMES }}"