Add vagrant

* Debian 7
* Apache
* PHP FPM
* PHP 5.5
* HHVM
* Composer
* MariaDB
* node.js with Grunt and Bower
The default error throws when the "vagrant-hostmanager" plugin is missing is ambiguous. 

> Unknown configuration section 'hostmanager'.

Maybe we can test the presence of the plugin here and throws a more comprehensive error when the plugin is not installed.

Something like :

> The "vagrant-hostmanager" plugin is missing. Install it using the following command :
>
> $ vagrant plugin install vagrant-hostmanager