Code clean-up and refactoring.

* Removed unneeded recipes.
* Added the git recipe needed for drush.
Files clean up.

Removed unneeded directory.
Recipes clean-up and refactoring.

* Utilities should be in a base role or equivalent and not in a drupal
recipe.
* Removed meaningless placeholders.
Improved metadata

* Correct metadatas.
* Version bump.
* Restrict support for Ubuntu.
Code refactor on the default recipe.
Move to using composer cookbook.

* Removed custom composer code.
* Added composer recipe dependency.
Added new roles.

* Added role "admin-user" for nodes to have admin user.
* Added role "base" for nodes to have commun utilities.
Added missed Composer dependency and new swap role.
Varnish recipe and initial cookbook attributes

* Added ommited php-gd module needed for Drupal.
* Recipe for Varnish setup on Drupal site.
* Moved cookbook specific attributes under the "Drupal" array.
* Added Vagrant cachier configuration.
Merge pull request #9 from rhabbachi/master

Varnish support and multiple additions.