Fixes setting auth cookie during install, removes some try/catch/swallow with some error messaging, converts some String -> string and == false updates.

src/Umbraco.Core/Models/UserExtensions.cs

@@ -2,6 +2,7 @@
 using System.Globalization;
 using System.Linq;
 using System.Threading;
+using Umbraco.Core.Models.Identity;
 using Umbraco.Core.Models.Membership;
 using Umbraco.Core.Services;