Add basic memento pattern

src/MememntoPattern/Employee/EmployeeExample.cs

@@ -0,0 +1,41 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace MememntoPattern.Employee
+{
+    public class EmployeeExample
+    {
+        public void Run()
+        {
+            Caretaker caretaker = new Caretaker();
+            Employee e = new Employee();
+            e.Name = "Ghiuri";
+            e.Address = "Stairway to heaven";
+
+            Console.WriteLine("First saved address: {0}", e.Address);
+            caretaker.Save(e);
+
+            e.Address = "Highway to hell";
+
+            Console.WriteLine("Last saved address: {0}", e.Address);
+
+            caretaker.Save(e);
+
+            e.Address = "Home of the brave"; // No save, no home, no address
+
+            Console.WriteLine("Address before revert: {0}", e.Address);
+
+            caretaker.Revert(e);
+
+            Console.WriteLine("First reverted Address: {0}", e.Address);
+
+            caretaker.Revert(e);
+
+            Console.WriteLine("Second reverted Address: {0}", e.Address);
+
+        }
+       
+    }
+}