Change directories to allow the autoload-dev

[EmanueleMinotto]

In order to allow the autoload-dev and the use of the subject class in tests, there should be the switch from PSR-4 in the repository's root to PSR-4 in src + tests.

From:

/
|-- Admin
|-- Command
|-- DependencyInjection
|-- Tests
    |-- Admin
    |-- Command
    |-- DependencyInjection

To:

/
|-- src
    |-- Admin
    |-- Command
    |-- DependencyInjection
|-- tests
    |-- Admin
    |-- Command
    |-- DependencyInjection

This will also allow us to do:

<?php

namespace Ae\FeatureBundle\DependencyInjection;

class FooTest extends \PHPUnit_Framework_TestCase
{
    protected function setUp()
    {
        $this->foo = new Foo(); // without the use
    }
}