Improve haproxy.cfg (#473)

* Use more readable 'listen' section
* Explicitely defined check options
* Enable stats dashboard
* Close HAProxy connections to a backend server when it's marked as down.

haproxy.cfg

@@ -10,12 +10,16 @@ defaults
     timeout server 30m
     timeout check 5s
 
-frontend ft_postgresql
+listen stats
+    mode http
+    bind *:7000
+    stats enable
+    stats uri /
+
+listen batman
     bind *:5000
-	default_backend bk_db
-
-backend bk_db
     option httpchk
-
+    http-check expect status 200
+    default-server inter 3s fall 3 rise 2 on-marked-down shutdown-sessions
     server postgresql_127.0.0.1_5432 127.0.0.1:5432 maxconn 100 check port 8008
     server postgresql_127.0.0.1_5433 127.0.0.1:5433 maxconn 100 check port 8009