add exit command-method in CLI project.

SmoulderingBeachBallCLI/ConsoleCommands.fs

@@ -5,9 +5,12 @@
         open Console.Waterworks
         open SmoulderingBeachBall
         open SmoulderingBeachBall.Services
+        open System
 
         let test () = "This program is working."
 
+        let exit () = Environment.Exit (Environment.ExitCode)
+
         let ``draw-image`` () =
             // makeImage 
             //"Image completed."