Bootstrap3 - Navbar : Add navbar's markupId in the data-target of the collaspe button instead of the ".navbar-ex-collapse"

With the current code when you add several navbars in the same page, the collapse buttons collapse and expand all the navbars!
This is due to the data-target=".navbar-ex-collapse".

I've changed the code so that each collapse button collapse only the navbar it depends on by using the markupId of the navbar.