Using the now documented `options` property of the `conf` resource, it
is now possible to pass arbitrary values to the underlying template.
This is most useful when the conf template is overridden via
template_cookbook (taken from one's own cookbook and not from the apache2 cookbook)

Example:
  apache2_conf 'custom' do
    template_cookbook 'test'
    options(
      index_ignore: '. .secret *.gen',
      index_charset: 'UTF-8'
    )
  end

Signed-off-by: Antoine Mazeas <antoine@karthanis.net>