Changes the Preview Index.cshtml to use a real model instead of viewdata, adds the correct razor web.config for these preview views, changes the enabled feature to be able to inject a razor view instead of strings

src/Umbraco.Web/Features/UmbracoFeatures.cs

@@ -14,6 +14,7 @@ namespace Umbraco.Web.Features
         public UmbracoFeatures()
         {
             Disabled = new DisabledFeatures();
+            Enabled = new EnabledFeatures();
         }
         
         /// <summary>