Product (multiplication)

```
/**
*  Returns the product of some numeric properties and numeric constants
*
*  Example: 6 * 7 * 2 = 84
*
*  Usage:
*    a: 6,
*    b: 7,
*    c: 2,
*    d: product('a', 'b', 'c'), // 84
*    e: product('a', 'b', 'c', 2) // 168
*/
```

JSBin to play with: http://emberjs.jsbin.com/qutak/7/edit?js,output

I know, and I think is an acceptable tradeoff. I was just wondering if `Ember.computed.literal` is going to make it into ember anytime soon.

But even if that happens, if people starts using it, it will work because it will still fall in the second branch of the if-else-if. So :+1:  for me.