Do not vendor cookbooks using Berkshelf anymore

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

cookbooks/users/libraries/osx_helper.rb

@@ -1,29 +0,0 @@
-module Users
-  # Helpers for Users
-  module OsxHelper
-    def dscl(*args)
-      host = '.'
-      stdout_result = ''
-      stderr_result = ''
-      cmd = "dscl #{host} -#{args.join(' ')}"
-      status = shell_out(cmd)
-      status.stdout.each_line { |line| stdout_result << line }
-      status.stderr.each_line { |line| stderr_result << line }
-      [cmd, status, stdout_result, stderr_result]
-    end
-
-    def safe_dscl(*args)
-      result = dscl(*args)
-      return '' if (args.first =~ /^delete/) && (result[1].exitstatus != 0)
-      raise(Chef::Exceptions::Group, "dscl error: #{result.inspect}") unless result[1].exitstatus == 0
-      raise(Chef::Exceptions::Group, "dscl error: #{result.inspect}") if result[2] =~ /No such key: /
-      result[2]
-    end
-
-    def gid_used?(gid)
-      return false unless gid
-      groups_gids = safe_dscl('list /Groups gid')
-      !!(groups_gids =~ Regexp.new("#{Regexp.escape(gid.to_s)}\n"))
-    end
-  end
-end