Shutdown runtime again

Rocket.Unturned/UnturnedImplementation.cs

@@ -103,8 +103,7 @@ namespace Rocket.Unturned
 
         private void OnServerShutdown()
         {
-            //runtime.Shutdown();
-            //Todo: Add Shutdown to IRuntime
+            runtime.Shutdown();
         }
 
         private void OnPlayerDamaged(SDG.Unturned.Player uPlayer, ref EDeathCause cause, ref ELimb limb, ref CSteamID killerId, ref Vector3 direction, ref float damage, ref float times, ref bool canDamage)