Yaml parser

In tests with Yaml parser, I used Symfony\Yaml and Yaml (Pecl).

The Yaml (Pecl) was the best for do it, because the format generated is more like the Ansible playbook.yml, unlike the Symfony\Yaml.

Look the tests and results:

yaml.php
```php
<?php

require 'vendor/autoload.php';

use Symfony\Component\Yaml\Dumper;

$dumper = new Dumper();

$yaml = array(
    array(
        'name' => 'Nginx - Install Webserver',
        'action' => 'pkg=nginx state=installed',
    ),
    array(
        'name' => 'Nginx - Create host folder',
        'file' => 'path={{ document_root }} state=directory'
    ),
    array(
        'name'     => 'Nginx - Configure Host',
        'template' => 'src=files/nginx.conf dest={{ nginx_folder }}/sites-available/{{ server_name }}'
    ),
    array(
        'name'    => 'Nginx - Applying configuration',
        'command' => 'ls -s {{ nginx_folder }}/sites-available'
    )
);
// Symfony\Yaml
print_r($dumper->dump($yaml));

// Yaml (Pecl)
print_r(yaml_emit($yaml));
```

Results:
```
// Symfony\Yaml
[{ name: 'Nginx - Install Webserver', action: 'pkg=nginx state=installed' }, { name: 'Nginx - Create host folder', file: 'path={{ document_root }} state=directory' }, { name: 'Nginx - Configure Host', template: 'src=files/nginx.conf dest={{ nginx_folder }}/sites-available/{{ server_name }}' }, { name: 'Nginx - Applying configuration', command: 'ls -s {{ nginx_folder }}/sites-available' }]

// Yaml (Pecl)
---
- name: Nginx - Install Webserver
  action: pkg=nginx state=installed
- name: Nginx - Create host folder
  file: path={{ document_root }} state=directory
- name: Nginx - Configure Host
  template: src=files/nginx.conf dest={{ nginx_folder }}/sites-available/{{ server_name
    }}
- name: Nginx - Applying configuration
  command: ls -s {{ nginx_folder }}/sites-available
...
```

In this case, I propose that we should use YAML (Pecl).