Array.prototype.sum

@Description: Add up the values in an array
@File: Array/prototype/sum.js
@Author: Paul Visco
@Version: 1.1 11/19/07
@Return: Number Returns the sum of all the values in an array
@Example:

var myArray = [5, 5, 10, 15];
var answer = myArray.sum();
//answer =35;