Setup basic code for login.

API/Entities/AppUser.cs

@@ -0,0 +1,28 @@
+using System;
+using System.ComponentModel.DataAnnotations;
+using API.Entities.Interfaces;
+
+
+namespace API.Entities
+{
+    public class AppUser : IHasConcurrencyToken
+    {
+        public int Id { get; set; }
+        public string UserName { get; set; }
+        public byte[] PasswordHash { get; set; }
+        public byte[] PasswordSalt { get; set; }
+        public DateTime Created { get; set; } = DateTime.Now;
+        public DateTime LastActive { get; set; }
+
+        [ConcurrencyCheck]
+        public uint RowVersion { get; set; }
+
+        public void OnSavingChanges()
+        {
+            RowVersion++;
+        }
+        
+        
+        
+    }
+}