set up a test subdir with cc:public (#1215)

diff --git a/test/pagespeed_test.conf.template b/test/pagespeed_test.conf.template
index 6a4a3b3..e3a9cda 100644
--- a/test/pagespeed_test.conf.template
+++ b/test/pagespeed_test.conf.template
@@ -1880,6 +1880,11 @@
         "http://$host:@@PRIMARY_PORT@@/mod_pagespeed_test/ipro/instant/"
         "@@SERVER_ROOT@@/mod_pagespeed_test/ipro/instant/";
 
+    location /mod_pagespeed_test/public/ {
+      add_header "Cache-Control" "public, max-age=600";
+      pagespeed PreserveUrlRelativity off;
+    }
+
     pagespeed EnableFilters remove_comments;
 
     # Test LoadFromFile mapping by mapping one dir to another.