Flexslider changing max items

HTML

<link rel="stylesheet" href="//cdnjs.cloudflare.com/ajax/libs/flexslider/2.2.2/flexslider-min.css">
<script src="//cdnjs.cloudflare.com/ajax/libs/flexslider/2.2.2/jquery.flexslider-min.js"></script>
<div class="flexslider js-slider">
    <ul class="slides">
        <li>
            <img src="http://lorempixel.com/150/150/animals" />
        </li>
        <li>
            <img src="http://lorempixel.com/150/150/people" />
        </li>
        <li>
            <img src="http://lorempixel.com/150/150/abstract" />
        </li>
        <li>
            <img src="http://lorempixel.com/150/150/food" />
        </li>
        <li>
            <img src="http://lorempixel.com/150/150/nature" />
        </li>
        <li>
            <img src="http://lorempixel.com/150/150/cats" />
        </li>
        <li>
            <img src="http://lorempixel.com/150/150/city" />
        </li>
    </ul>
</div>

CSS

.flexslider { width: 600px}
.flexslider li { 
    width: 150px
    margin: 0 0 0 20px;
    padding: 0;
    position: relative;
    background-color: #FFF;
    float: left;
    list-style-type: none;
    -webkit-box-sizing: border-box;
       -moz-box-sizing: border-box;
            box-sizing: border-box;
    padding: 0;
    display: block;
}

JavaScript

/**
 * @file RD Slider - RD Slider is a slider that has 3 slides visible.<br>
 * Created: 03/03/2014<br>
 * Modified: 05/16/2014
 * @requires jquery-1.9.1.min.js
 * @requires jquery-flexslider.2.2.2.min.js
 */

/**
 * RD - The global Everyday Health Namespace
 * @namespace
 * @type {Object}
 * @global
 */
window.RD = window.RD || {};

/**
 * Immediately-Invoked Function Expression.
 *
 * @function
 * @param {object} $ - Global jQuery object.
 * @param {object} w - Global window object.
 */
(function ($, w) {

    // strict JS
    'use strict';

    /**
     * Create instance of SliderConstructor<br>
     * Modified: 04/03/2014
     *
     * @constructor
     * @name RD.SliderConstructor
     * @param {jQuery|string} controls - Selector string or jQuery object for the controls container element.
     * @param {jQuery|string} share - Selector string or jQuery object for the share container elements.
     * @param {jQuery|string} target - Selector string or jQuery object for the slider container element.
     * @property {jQuery} $controls - jQuery object representing the slider controls element.
     * @property {jQuery} $shareTarget - jQuery object representing the share elements.
     * @property {jQuery} $sliderTarget - jQuery object representing the slider elements.
     * @author Richard Dillman <[email protected]>
     */
    w.RD.SliderConstructor = function (target, controls) {
        this.$controls = (controls instanceof $ && controls) || $(controls);
        this.$sliderTarget = (target instanceof $ && target) || $(target);
        this.$w = $(w);
    };

    /**
     * Inheritable methods of SliderConstructor.
     *
     * @type {Object}
     * @lends RD.SliderConstructor#
     */
    w.RD.SliderConstructor.prototype = {

        /**
         * Initialization methods for RD.Slider
         * Modified: 04/03/2014
         *
         * @inner
         * @param {object} data - The body data array.
         * @param {boolean} data.isMobile -...