Added missing "root" files
First successful packing of Laravel's Illuminate DB classes, added Plugins Class packer

* We can display a "Hello world" through Slim and a Plugin action with only 11 included files, with Illuminate DB & Support libraries
* Added a "PackingProfilesManager" Service
* Added some Interfaces for our core components
* we now have "packed PHP code" metadata, so that we can now a bit what's inside a Pack
* Added "utils.string" & "utils.io" Boot Services
* Plugins can now request Classes packing
* Packed PHP Classes are now wrapped in a "if (!class_exists())" condition, so that we don't trigger an error if our "Packed PHP" loader and Composer Loader both try to define a Class
* added missing main INI config file
* Added Illuminate DB, Validation & Cache libraries to our composer.json
* Added a gulpfile with live PHP Packs reloading