As you are aware support for multi level drop down menu was removed in Bootstrap 3. I previously posted a tutorial and the necessary code to allow you to support multi-level menus in WordPress using Bootstrap. However, in my rush to get the post up, apparently I made a few errors in the code and CSS.
Since the changes I made were rather significant I have just uploaded the new files to my Github. You can check it out there: https://github.com/jeffmould/multi-level-bootstrap-menu.
To see the menu in action you can go to http://theboot.fenwickmedia.com for a demo.