/// <summary>
        /// Load a list of all possible categories.
        /// </summary>
        /// <param name="context"></param>
        /// <returns></returns>
        public static HashSet <string> GetList(ControllerContext controllerContext, HttpContextBase context)
        {
            if (context.Application[APP_CACHE_KEY] == null)
            {
                CacheInitializer.InitializeEditorCache(controllerContext, context);
            }

            return((HashSet <string>)context.Application[APP_CACHE_KEY]);
        }
        /// <summary>
        /// Load the list of possible modules from the app cache, if the app cache does not contain the module types then it will load and store them.
        /// </summary>
        /// <param name="context"></param>
        /// <returns></returns>
        public static List <ColumnModuleType> GetList(ControllerContext controllerContext, HttpContextBase context)
        {
            if (context.Application[APP_CACHE_KEY] == null)
            {
                CacheInitializer.InitializeEditorCache(controllerContext, context);
            }

            return((List <ColumnModuleType>)context.Application[APP_CACHE_KEY]);
        }