Add message format support that can be used on complex localization strings

Add message about new and unread topics at the bottom of topics
move localization helper into lib

lib/javascripts/locale/cs.js

@@ -0,0 +1,9 @@
+MessageFormat.locale.cs = function (n) {
+  if (n == 1) {
+    return 'one';
+  }
+  if (n == 2 || n == 3 || n == 4) {
+    return 'few';
+  }
+  return 'other';
+};