Allow Underscore to accept both jQuery objects and Arrays

Related issue: https://github.com/borisyankov/DefinitelyTyped/issues/193

Of course we could overload all underscore functions to get jquery as well as array parameters but I think having a common list interface is better.

// Used as common interface between Arrays and jQuery objects
interface IList {
    [index: number]: any;
    length: number;
}

Thanks