function xmlEscape(string) {
  return string
    .replace(/&/g, '&amp;')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/"/g, '&quot;');
}
DELETE `filename` with optional `headers`
and callback `fn` with a possible exception and the response.

@param {String} filename
@param {Object|Function} headers
@param {Function} fn
@api public