Allow to create new class without write current namespace before class

- implement

- added tests

Example

```zephir
class EntityManager
{
	protected unitOfWork;
	
    public function __construct()
	{
		// before this commit i need to write all namespace \Phalcon\ORM\UnitOfWork
		let this->unitOfWork = new UnitOfWork();
	}
}
```

Review me @phalcon