added test for function in config.data_order

spec/data-spec.js

+var describe = window.describe,
+    expect = window.expect,
+    it = window.it,
+    beforeEach = window.beforeEach;
+
+describe('c3 chart data', function () {
+    'use strict';
+
+    var chart, d3;
+
+    beforeEach(function () {
+        window.initDom();
+        chart = window.c3.generate({
+            data: {
+                columns: [
+                    ['data1', 30, 200, 100, 400, 150, 250],
+                    ['data2', 50, 20, 10, 40, 15, 25],
+                    ['data3', 150, 120, 110, 140, 115, 125]
+                ],
+                order: function () {
+                    return 0;
+                }
+            }
+        });
+        d3 = chart.internal.d3;
+    });
+
+    describe('function in data.order', function () {
+        it('should return false in isOrderAsc and isOrderDesc functions', function () {
+            expect(chart.internal.isOrderAsc() || chart.internal.isOrderDesc()).toBe(false);
+        });
+    });
+});