Provide generic Command, Event and Query implementations

[nilportugues]

Because DTO are easy to use, but I require passing an object implementing an Interface, provide helper objects. For instance:

<?php
use NilPortugues\MessageBus\CommandBus\Contracts\Command as CommandInterface;

class Command implements CommandInterface
{
    public function __get($property) 
    {
            if (property_exists($this, $property)) {
                return $this->$property;
            }
    }

    public function __set($property, $value) 
    {
            $this->$property = $value;
    }
}