Extract Thelia core

_WIP: Extract all the modules_

**This PR allows a new management in new Thelia projects.**

Like the symfony/symfony way to extract the components, we are now able to extract Thelia "components" into different repositories, allowing projects to bootstrap their own thelia with their composer.json

Having their _own_ composer.json, people can delete default modules they don't use and still have thelia updates, require theirs with composer, and do the same for templates. 

All default modules has received a composer.json and are now hosted on [thelia modules account](https://github.com/thelia-modules)

A "standart" bootstrap of Thelia with composer is / will be available on https://github.com/thelia/thelia-project.

![composer](https://cloud.githubusercontent.com/assets/6106094/5538743/6d1eae56-8ab8-11e4-95fb-17b55cd9aa4f.jpg)