Replaces more calls to legacy UmbracoSettings with the new configuration section, fixes loads of null checks when dealing with package repository APIs

src/Umbraco.Web/Cache/DistributedCacheExtensions.cs

@@ -2,6 +2,7 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 using Umbraco.Core;
+using Umbraco.Core.Configuration;
 using Umbraco.Core.Models;
 using umbraco;
 using umbraco.cms.businesslogic.web;