Enable hoverIntent jQuery integration

This change allows [`hoverIntent`](https://github.com/briancherne/jquery-hoverIntent) to be used instead of jQuery's native `hover`. If [`jquery.hoverIntent.js`](https://github.com/briancherne/jquery-hoverIntent/blob/master/jquery.hoverIntent.js) isn't included, then it falls back to the standard hover behavior.

I needed this for a project with a [megamenu-style, full-width navbar](http://geedmo.github.io/yamm3/) set 100px or so below the top of window. When users moused over/past the navbar from the header to the content area, the dropdown triggered immediately and effectively blocked most of the web page. Adding a slight delay prevent those accidental triggers.

My changes may be too far out of the scope of this plugin, but I thought I'd submit a pull request in case this is useful to anyone else.
I like your idea, but this is a *very* dangerous idea as this would change hover *everywhere* in your application (`$.fn` is a shortcut for `jQuery.prototype`).

HoverIntent is an oft asked-for feature. I don't like adding it by default, but if you can rework this not to change the hover prototype, I would definitely consider merging it.