Make the Chinese translations actually work

Before this change, the user must configure `lang="zh"` to use the CN version (neither `lang="zh_CN"` nor `lang="zh_TW"` works).

isso/js/app/i18n.js

@@ -2,8 +2,8 @@ define(["app/config", "app/i18n/bg", "app/i18n/cs", "app/i18n/de",
         "app/i18n/en", "app/i18n/fa", "app/i18n/fi", "app/i18n/fr",
         "app/i18n/hr", "app/i18n/ru", "app/i18n/it", "app/i18n/eo",
         "app/i18n/sv", "app/i18n/nl", "app/i18n/el_GR", "app/i18n/es",
-        "app/i18n/vi", "app/i18n/zh_CN"],
-        function(config, bg, cs, de, en, fa, fi, fr, hr, ru, it, eo, sv, nl, el, es, vi, zh) {
+        "app/i18n/vi", "app/i18n/zh_CN", "app/i18n/zh_TW"],
+        function(config, bg, cs, de, en, fa, fi, fr, hr, ru, it, eo, sv, nl, el, es, vi, zh_CN, zh_TW) {
 
     "use strict";
 
@@ -23,7 +23,8 @@ define(["app/config", "app/i18n/bg", "app/i18n/cs", "app/i18n/de",
         case "sv":
         case "nl":
         case "vi":
-        case "zh":
+        case "zh_CN":
+        case "zh_TW":
             return function(msgs, n) {
                 return msgs[n === 1 ? 0 : 1];
             };
@@ -70,7 +71,8 @@ define(["app/config", "app/i18n/bg", "app/i18n/cs", "app/i18n/de",
         sv: sv,
         nl: nl,
         vi: vi,
-        zh: zh
+        zh_CN: zh_CN,
+        zh_TW: zh_TW
     };
 
     var plural = pluralforms(lang);