Vendor the external cookbooks

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

cookbooks/apt/libraries/helpers.rb

@@ -0,0 +1,49 @@
+#
+# Cookbook:: apt
+# Library:: helpers
+#
+# Copyright:: 2013-2017, Chef Software, Inc.
+#
+# 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.
+#
+
+module Apt
+  # Helpers for apt
+  module Helpers
+    # Determines if apt is installed on a system.
+    #
+    # @return [Boolean]
+    def apt_installed?
+      !which('apt-get').nil?
+    end
+
+    # Finds a command in $PATH
+    #
+    # @return [String, nil]
+    def which(cmd)
+      ENV['PATH'] = '' if ENV['PATH'].nil?
+      paths = (ENV['PATH'].split(::File::PATH_SEPARATOR) + %w(/bin /usr/bin /sbin /usr/sbin))
+
+      paths.each do |path|
+        possible = File.join(path, cmd)
+        return possible if File.executable?(possible)
+      end
+
+      nil
+    end
+  end
+end
+
+Chef::Recipe.send(:include, ::Apt::Helpers)
+Chef::Resource.send(:include, ::Apt::Helpers)
+Chef::Provider.send(:include, ::Apt::Helpers)