Adding 2FA Authenticator Support (#66)

* Adding support for 2fa, more auth options

* WIP getting auth stuff working

* Added Manage views. 2FA working now for MVC app.

* Switching to using a controller for no-UI logout scenario

* Adding Razor Pages impl of 2FA auth stuff. Works.

src/WebRazorPages/Extensions/EmailSenderExtensions.cs

@@ -0,0 +1,22 @@
+using ApplicationCore.Interfaces;
+using System.Text.Encodings.Web;
+using System.Threading.Tasks;
+
+namespace Microsoft.AspNetCore.Mvc
+{
+    public static class EmailSenderExtensions
+    {
+        public static Task SendEmailConfirmationAsync(this IEmailSender emailSender, string email, string link)
+        {
+            return emailSender.SendEmailAsync(email, "Confirm your email",
+                $"Please confirm your account by <a href='{HtmlEncoder.Default.Encode(link)}'>clicking here</a>.");
+        }
+
+        public static Task SendResetPasswordAsync(this IEmailSender emailSender, string email, string callbackUrl)
+        {
+            return emailSender.SendEmailAsync(email, "Reset Password",
+                $"Please reset your password by <a href='{HtmlEncoder.Default.Encode(callbackUrl)}'>clicking here</a>.");
+        }
+    }
+
+}