Do not vendor cookbooks using Berkshelf anymore

Instead, use the Berkshelf support in knife-solo and the
vagrant-berkshelf plugin on Vagrant

cookbooks/composer/recipes/default.rb

@@ -1,12 +0,0 @@
-#
-# Cookbook Name:: composer
-# Recipe:: default
-#
-# Copyright (c) 2016, David Joos
-#
-
-include_recipe 'composer::install'
-
-if node['composer']['install_globally']
-  include_recipe 'composer::global_configs'
-end