allow caching of json files

ilib performs quite a number of GET requests to JSON files (strings, plurals, localeinfo). Since enyo.Ajax is used, each of these GET requests is performed with a random query string appended in order to prevent cache usage. While this might be a good idea for Ajax requests in general, this makes no sense for the ilib json files - their cache behaviour has to be identical to the application javascript files. This patch deactivates the cacheBust feature of all Ajax requests in glue.js.