Use Chef::Cookbook::ChefIgnore in policyfile export

This could maybe be a bit more in depth. The way I did it automatically
excludes all dotfiles and only really checks the base level directories.
I'm not sure if we need to get any more in depth in the chefignore here.

Fixes #519

Author: onlyhavecans

lib/chef-dk/policyfile_services/export_repo.rb

@@ -21,6 +21,8 @@
 
 require 'archive/tar/minitar'
 
+require 'chef/cookbook/chefignore'
+
 require 'chef-dk/service_exceptions'
 require 'chef-dk/policyfile_lock'
 require 'chef-dk/policyfile/storage_config'
@@ -152,7 +154,8 @@ def copy_cookbook(lock)
         dirname = "#{lock.name}-#{lock.dotted_decimal_identifier}"
         export_path = File.join(staging_dir, "cookbooks", dirname)
         metadata_rb_path = File.join(export_path, "metadata.rb")
-        FileUtils.cp_r(lock.cookbook_path, export_path)
+        FileUtils.mkdir(export_path) if not File.directory?(export_path)
+        FileUtils.cp_r(cookbook_files_to_copy(lock.cookbook_path), export_path)
         FileUtils.rm_f(metadata_rb_path)
         metadata = lock.cookbook_version.metadata
         metadata.version(lock.dotted_decimal_identifier)
@@ -164,6 +167,13 @@ def copy_cookbook(lock)
         end
       end
 
+      def cookbook_files_to_copy(cookbook_path)
+        chefignore_file = File.join(cookbook_path, 'chefignore')
+        chefignore = Chef::Cookbook::Chefignore.new(chefignore_file)
+        Dir.glob(File.join(cookbook_path, '*')).
+          reject{ |f| chefignore.ignored?(File.basename(f)) }
+      end
+
       def create_policyfile_data_item
         lock_data = policyfile_lock.to_lock.dup