refactor app directory structure and add tests

tests/node_modules/nightwatch/lib/api/client-commands/useXpath.js

@@ -0,0 +1,27 @@
+var util = require('util');
+var locateStrategy = require('./_locateStrategy.js');
+
+/**
+ * Sets the locate strategy for selectors to xpath, therefore every following selector needs to be specified as xpath.
+ *
+ * ```
+ * this.demoTest = function (browser) {
+ *   browser
+ *     .useXpath() // every selector now must be xpath
+ *     .click("//tr[@data-recordid]/span[text()='Search Text']");
+ * };
+ * ```
+ *
+ * @method useXpath
+ * @param {function} [callback] Optional callback function to be called when the command finishes.
+ * @api commands
+ */
+
+function Command() {
+  this.strategy = 'xpath';
+  locateStrategy.call(this);
+}
+
+util.inherits(Command, locateStrategy);
+
+module.exports = Command;