Feature/value holder generator

First implementation of the proxy generator for lazy value objects.

Usage:

```php
$config  = new \ProxyManager\Configuration();
$factory = new \ProxyManager\Factory\LazyLoadingValueHolderFactory($config);

$proxy = $factory->createProxy('stdClass', function () { echo('initializer!'); });

var_dump($proxy);
$proxy->initializeProxy(); // obviously ok with a correct initializer
```

Implemented:

 * lazy value object generator
 * facade factory to instantiate lazy objects
 * proxy autoloader, file locator and name inflector
 * configuration mini-DIC to simplify usage of the project's functionality

TBD: 

 * tests tests tests!
 * aggregate the lazy loading + value holder interfaces for type hinting