Do not vendor cookbooks using Berkshelf anymore

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

cookbooks/nodejs/attributes/repo.rb

@@ -1,12 +0,0 @@
-case node['platform_family']
-when 'debian'
-  default['nodejs']['install_repo'] = true
-  default['nodejs']['repo']         = 'https://deb.nodesource.com/node_6.x'
-  default['nodejs']['keyserver']    = 'keyserver.ubuntu.com'
-  default['nodejs']['key']          = '1655a0ab68576280'
-when 'rhel', 'amazon'
-  default['nodejs']['install_repo'] = true
-  release_ver = platform?('amazon') ? 6 : node['platform_version'].to_i
-  default['nodejs']['repo']         = "https://rpm.nodesource.com/pub_6.x/el/#{release_ver}/$basearch"
-  default['nodejs']['key']          = 'https://rpm.nodesource.com/pub/el/NODESOURCE-GPG-SIGNING-KEY-EL'
-end