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 actually don't want user to directly instantiated this class.
Instead they invoke ``CommandBase::autoloadCommands($path)``
They can use any directory path if they'd like to.