roles/haproxy: Add support for Debian hosts

Debian does not support system-wide SSL cipher suite profiles of course,
so these options need to be specified explicitly when deploying HAProxy
on Debian-based machines.

roles/haproxy/tasks/main.yml

@@ -1,3 +1,9 @@
+- name: load distribution-specific values
+  include_vars: '{{ item }}'
+  with_first_found:
+  - '{{ ansible_distribution }}.yml'
+  - defaults.yml
+
 - name: ensure haproxy is installed
   package:
     name=haproxy