Update VKontakteAuthenticationHandler.cs

Email support. VK send it with access_token

src/Owin.Security.Providers.VKontakte/VKontakteAuthenticationHandler.cs

@@ -95,6 +95,10 @@ namespace Owin.Security.Providers.VKontakte
                 var user = await GetUser(response, accessToken);
 
                 var context = CreateAuthenticatedContext(user, accessToken, properties);
+    
+                // Email support. VK send it with access_token
+                context.Identity.AddClaim(new Claim(ClaimTypes.Email, response["email"].ToString(), XmlSchemaString,
+                    Options.AuthenticationType));
 
                 await Options.Provider.Authenticated(context);
 
@@ -226,4 +230,4 @@ namespace Owin.Security.Providers.VKontakte
             return context.IsRequestCompleted;
         }
     }
-}
+}