ASP.NET Identity Registrar [Legacy]

using EPiServer.Commerce.Security;
using EPiServer.Framework;
using EPiServer.Framework.Initialization;
using EPiServer.ServiceLocation;
using EPiServer.Web;
using log4net;
using Microsoft.AspNet.Identity;
using System;
using System.Collections.Generic;
using System.Configuration;
using System.Linq;
using System.Web.Routing;
using System.Web.Security;

namespace WebApplication1
  {
    [InitializableModule]
    [ModuleDependency(typeof(Mediachase.Commerce.Initialization.CommerceInitialization),
                      typeof(EPiServer.Commerce.Initialization.InitializationModule))]
    public class InitializeCommerceSiteModule : IConfigurableModule
      {
        public void Initialize(InitializationEngine context)
          {
          }
        public void Preload(string[] parameters)
          {
          }
        public void Uninitialize(InitializationEngine context)
          {
          }
        public void ConfigureContainer(ServiceConfigurationContext context)
          {
            context.Container.Configure(ce =>
              {
                ce.For<IRegistrar>().Singleton().Use(() => 
                  new IdentityRegistrar<ApplicationUser>(new ApplicationUserManager(new UserStore<ApplicationUser>(new ApplicationDbContext()))));
              });
          }
      }
  }

[HttpPost]
[AllowAnonymous]
[ValidateAntiForgeryToken]
public async Task Register(FormCollection model)
  {
    if (ModelState.IsValid)
      {
        string firstName = model["Email"];
        string lastName = model["Email"];
        string emailAddress = model["Email"];
        string password = model["Password"];
        var principal = await Task.Run(() => _registrar.CreateUser(emailAddress, password, emailAddress));
                
        // Now create an account in the ECF 
        CustomerContact customerContact;
        if (_registrar is CustomerContactRegistrar)
          {
            customerContact = CustomerContext.Current.GetContactByUserId(
              new MapUserKey(s => new ConvertStringUserKey()).ToTypedString(principal.Identity.Name));
          }
        else
          {
            customerContact = CustomerContact.CreateInstance(principal);
          }
        customerContact.FirstName = firstName;
        customerContact.LastName = lastName;
        customerContact.RegistrationSource = String.Format("{0}, {1}", this.Request.Url.Host, SiteContext.Current);
        customerContact["Email"] = emailAddress;
        customerContact.SaveChanges();
        await Task.Run(() =>_registrar.SignIn
          (
            new AuthenticationProperties()
              {
                IsPersistent = false
              },
              principal.Identity as ClaimsIdentity
          );
        return RedirectToAction("Index");
      }

    // If we got this far, something failed, redisplay form
    return View(model);
  }