Provide single endpoint to load all node message catalogs

Replaces potentially dozens of http requests with one or two.

red/runtime/i18n.js

@@ -98,6 +98,7 @@ function init() {
 
 function getCatalog(namespace,lang) {
     var result = null;
+    lang = lang || defaultLang;
     if (resourceCache.hasOwnProperty(namespace)) {
         result = resourceCache[namespace][lang];
         if (!result) {
@@ -105,9 +106,6 @@ function getCatalog(namespace,lang) {
             if (langParts.length == 2) {
                 result = resourceCache[namespace][langParts[0]];
             }
-            if (!result) {
-                return resourceCache[namespace][defaultLang];
-            }
         }
     }
     return result;