Did some refactoring...

* Updated autoload.php
* Replaced 'system.php' with 'load_system_paths.php'. Refactored the code base to reflect these changes
* Using Composer to maintain 3rd party libraries
* Added 'EventDispatcher' Symfony Component code to repo
* Moved 'Acms\Core' and 'PhpRbac' code from 'packages' to 'src'
* Other misc changes
Working up updating 'Creating a Module' code and tutorial
Adding beginnings of 'ModuleSystem' core libraries to repo
Updated comment to reflect more accurate description