use much better default haproxy values with explanations

slapos/recipe/erp5/template/haproxy.cfg.in

@@ -9,10 +9,19 @@ defaults
   retries 1
   option redispatch
   maxconn 2000
-  timeout server 3000s
-  timeout queue 5s
-  timeout connect 10s
-  timeout client 3600s
+  # it is useless to have timeout much bigger than the one of apache.
+  # By default apache use 300s, so we set slightly more in order to
+  # make sure that apache will first stop the connection.
+  timeout server 305s
+  # Stop waiting in queue for a zope to become available.
+  # If no zope can be reached after one minute, consider the request will
+  # never succeed.
+  timeout queue 60s
+  # The connection should be immediate on LAN,
+  # so we should not set more than 5 seconds, and it could be already too much
+  timeout connect 5s
+  # As requested in haproxy doc, make this "at least equal to timeout server".
+  timeout client 305s
 
 listen %(name)s %(ip)s:%(port)s
   cookie  SERVERID insert