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/default.rb

@@ -1,5 +0,0 @@
-default['firewall']['allow_ssh'] = false
-default['firewall']['allow_winrm'] = false
-default['firewall']['allow_mosh'] = false
-default['firewall']['allow_loopback'] = false
-default['firewall']['allow_icmp'] = false