Fix wget healthchecks to not use localhost

For a reason, current wget versions error out when using localhost instead
of 127.0.0.1 as the healthcheck for docker services. Probably has something
to do with dns resolution - either on docker or wget end, but have not
looked to deep into it.

roles/landingpage/templates/docker-stack.yml.j2

@@ -4,7 +4,7 @@ services:
   app:
     image: "{{ stack_image }}:{{ landingpage_version }}"
     healthcheck:
-      test: ["CMD", "wget", "--spider", "-q", "localhost"]
+      test: ["CMD", "wget", "--spider", "-q", "127.0.0.1"]
       interval: 1m
       timeout: 10s
       retries: 3