time-constants

Some constants for convenient amounts of time, in milliseconds

``js
'use strict';

const MILLISECONDS_PER_SECOND = 1000;
const SECONDS_PER_MINUTE = 60;
const MINUTES_PER_HOUR = 60;
const HOURS_PER_DAY = 24;
const DAYS_PER_WEEK = 7;
const MONTHS_PER_YEAR = 12;

const SECOND = MILLISECONDS_PER_SECOND;
const MINUTE = SECOND * SECONDS_PER_MINUTE;
const HOUR = MINUTE * MINUTES_PER_HOUR;
const DAY = HOUR * HOURS_PER_DAY;
const WEEK = DAY * DAYS_PER_WEEK;
const YEAR = DAY * 365.24;
const NORMAL_YEAR = DAY * 365;
const LEAP_YEAR = DAY * 366;
const DECADE = 10 * YEAR;
const HALF_YEAR = YEAR/2;
const AVERAGE_MONTH = YEAR/12;

module.exports = {
SECOND: SECOND
, MINUTE : MINUTE
, HOUR : HOUR
, DAY : DAY
, WEEK : WEEK
, YEAR : YEAR
, NORMAL_YEAR : NORMAL_YEAR
, LEAP_YEAR : LEAP_YEAR
, DECADE : DECADE
, HALF_YEAR: HALF_YEAR
, AVERAGE_MONTH : AVERAGE_MONTH
, MILLISECONDS_PER_SECOND : MILLISECONDS_PER_SECOND
, SECONDS_PER_MINUTE : SECONDS_PER_MINUTE
, MINUTES_PER_HOUR : MINUTES_PER_HOUR
, HOURS_PER_DAY : HOURS_PER_DAY
, DAYS_PER_WEEK : DAYS_PER_WEEK
, MONTHS_PER_YEAR : MONTHS_PER_YEAR

// ±100,000,000 days, the min and max dates allowed in ECMA Script.
// See: http://ecma-international.org/ecma-262/5.1/#sec-15.9.1.1
, MIN_DATE : new Date(-8.64E15)
, MAX_DATE : new Date(8.64E15)
};
``