acme: add haproxy support

Signed-off-by: Wakatatsu Ryou <lialosiu@gmail.com>

net/acme/files/acme.config

@@ -9,6 +9,7 @@ config cert 'example_wildcard'
 	option keylength 2048
 	option update_uhttpd 1
 	option update_nginx 1
+	option update_haproxy 0
 	list domains example.org
 	list domains sub.example.org
 	list domains *.sub.example.org
@@ -26,6 +27,7 @@ config cert 'example'
 	option keylength 2048
 	option update_uhttpd 1
 	option update_nginx 1
+	option update_haproxy 0
 	list domains example.org
 	list domains sub.example.org
 	option webroot ""