Command autoloading feature

This PR actually mix with 3 stuffs.

  - Command autoloading feature
  - A bug fix when throwing an ExecuteMethodNotDefinedException
  - make ProgramName of an Application be its sufficient part of $argv[0] only

I can re-organize it if you want.
I was intent to use this design, since I've seen some guys using '.class.php' or '.lib.php' as their extension. 

The ultimate solution should still use spl_auto_extensions() to find the match. Let's discuss it more.