Install socat where we install haproxy

Socat is useful for managing haproxy through the haproxy management
socket. Install it when we install haproxy.

Change-Id: Ie2b16cef62f661669756d24d4a69ac1683401268

playbooks/roles/haproxy/tasks/main.yaml

@@ -1,3 +1,7 @@
+- name: Install socat for haproxy management
+  package:
+    name: socat
+    state: present
 - name: Synchronize docker-compose directory
   synchronize:
     src: docker/