added two factor providers to user object

src/Core/Enums/TwoFactorProviderType.cs

@@ -2,6 +2,9 @@
 {
     public enum TwoFactorProviderType : byte
     {
-        Authenticator = 0
+        Authenticator = 0,
+        Email = 1,
+        Duo = 2,
+        YubiKey = 3
     }
 }

src/Core/Models/Table/User.cs

@@ -17,6 +17,7 @@ namespace Bit.Core.Models.Table
         public bool TwoFactorEnabled { get; set; }
         public TwoFactorProviderType? TwoFactorProvider { get; set; }
         public string AuthenticatorKey { get; set; }
+        public string TwoFactorProviders { get; set; }
         public string TwoFactorRecoveryCode { get; set; }
         public string EquivalentDomains { get; set; }
         public string ExcludedGlobalEquivalentDomains { get; set; }

src/Core/Models/TwoFactorProvider.cs

@@ -0,0 +1,12 @@
+using Bit.Core.Enums;
+using System.Collections.Generic;
+
+namespace Bit.Core.Models
+{
+    public class TwoFactorProvider
+    {
+        public bool Enabled { get; set; }
+        public bool Remember { get; set; }
+        public Dictionary<string, object> MetaData { get; set; }
+    }
+}