Vendor the external cookbooks

Knife-Zero doesn't include Berkshelf support, so vendoring everything in
the repo is convenient again

cookbooks/homebrew/recipes/install_formulas.rb

@@ -0,0 +1,33 @@
+#
+# Cookbook:: homebrew
+# Recipes:: install_casks
+#
+# Copyright:: 2014-2016, Chef Software, Inc <legal@chef.io>
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+include_recipe 'homebrew'
+
+node['homebrew']['formulas'].each do |formula|
+  if formula.class == Chef::Node::ImmutableMash
+    formula_options = formula.fetch(:options, '')
+    formula_options += ' --HEAD' if formula.fetch(:head, false)
+    package formula.fetch(:name) do
+      options formula_options.strip
+      version formula['version'] if formula.fetch(:version, false)
+    end
+  else
+    package formula
+  end
+end