Add wallabag docker deployment role

Added role of wallabag. Can take a subdomain alias to be presented on a
different uri than its stack name.

All services contain a healthcheck for docker swarm to be informed of
their status.

Copy whoami template to wallabag role

Change non-domain domain name to localhost

Fix correct handler notify naming

Allow setting different subdomain alias than name

Add meta information

roles/wallabag/vars/main.yml

@@ -0,0 +1,7 @@
+---
+
+stack:
+  name: wallabag
+  compose: "{{ lookup('template', 'docker-stack.yml.j2') | from_yaml }}"
+
+stack_image: "wallabag/wallabag"