menu.js: POST appears to be forbidden depending on the config

On our test server, an independent instance was not able to work using POST
and we had to put GET. It should be more widely accepted than POST.

browser/js/menu.js

@@ -37,7 +37,7 @@ function initMenu () {
             
             //detect if files are available
             $.ajax({
-                type: "POST",
+                type: "GET",
                 timeout: 5000,
                 crossDomain: true,
                 url: config.file_menu.path + config.file_menu.file[0],