Do not vendor cookbooks using Berkshelf anymore

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

cookbooks/firewall/attributes/ufw.rb

@@ -1,12 +0,0 @@
-default['firewall']['ufw']['defaults'] = {
-  ipv6: 'yes',
-  manage_builtins: 'no',
-  ipt_sysctl: '/etc/ufw/sysctl.conf',
-  ipt_modules: 'nf_conntrack_ftp nf_nat_ftp nf_conntrack_netbios_ns',
-  policy: {
-    input: 'DROP',
-    output: 'ACCEPT',
-    forward: 'DROP',
-    application: 'SKIP',
-  },
-}