toRFC2822() {
    return toTechFormat(this, "EEE, dd LLL yyyy HH:mm:ss ZZZ", false);
  }
Returns an RFC 2822-compatible string representation of this DateTime
@example DateTime.utc(2014, 7, 13).toRFC2822() //=> 'Sun, 13 Jul 2014 00:00:00 +0000'
@example DateTime.local(2014, 7, 13).toRFC2822() //=> 'Sun, 13 Jul 2014 00:00:00 -0400'
@return {string}