Merge pull request usablica#327 from connyay/issue-245

return this from exit - fixes usablica#245

Author: afshinm

intro.js

@@ -983,6 +983,7 @@
     },
     exit: function() {
       _exitIntro.call(this, this._targetElement);
+      return this;
     },
     refresh: function() {
       _setHelperLayerPosition.call(this, document.querySelector('.introjs-helperLayer'));