_.superlative Method to find most `superior` element in an array or object

Comparison is based on a Java-like comparator function that takes in two objects and returns truthy value if
first element is more superior to second else returns a falsy value

```javascript
var arr = [{a:'foo', b: 3}, {a:'bar', b: 1}, {a:'baz', b: 5}];

//This method call would return object with least value of `b`
_.superlative(arr, function (o1, o2) {
    return (o1.b < o2.b);
});

```

*This method is especially useful when composition of objects defines how they can be compared*