added AccessTokenExpiredException.cs

diff --git a/PokemonGo.RocketAPI/Exceptions/AccessTokenExpiredException.cs b/PokemonGo.RocketAPI/Exceptions/AccessTokenExpiredException.cs
new file mode 100644
index 0000000..5b2c9af
--- /dev/null
+++ b/PokemonGo.RocketAPI/Exceptions/AccessTokenExpiredException.cs
@@ -0,0 +1,12 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace PokemonGo.RocketAPI.Exceptions
+{
+    public class AccessTokenExpiredException : Exception
+    {
+    }
+}
\ No newline at end of file