Convert a Date object to a rfc-822 date string
RFC 1123 is an update to RFC 822 which specifies that the year MUST be 4 digits. As this library has always used 4 digits for the year, it is compatible with both.
var rfc822Date = require('rfc822-date');
console.log(rfc822Date(new Date())); // 'Mon, 13 Sep 2013 14:27:00 +0200'